My Trip to Bali 5

I think I have to wrap up my travel story with this entry. I get the feeling that it's taking too long. Anyways, I was happy that my friend joined me. He and I were supposed to spend two of our overlapping days together because I had told him earlier I would spend the last day of my trip by myself before I returned to Korea at night. So, he made his plans for himself for that day. But after five days of traveling alone, I couldn't imagine myself spending another day by myself. So, I impulsively booked a boat tour for my last day. I figured, that way, at least I would get a chance to make friends on the tour. I thought that was a great decision until we became friends with a nice Korean woman in our surf lesson. She was fun to talk to, and she said she had some friends she had met at her guest house. Funny thing about destiny: I would never have bothered to book a tour that I hadn't even planned if I knew I'd meet someone I could hang out with on my last day. Again, I was faced with a decision, and I decided (better: chose, this is less redundant) to stick with my original plans this time too. And this time, it turned out that wasn't totally wrong.

*** Very good, some minor tensing issues, but it didn't detract from the passage too much. Most of my corrections were word choice adjustments so that it looks more like a native writer.

I Find It Very Difficult.

I've been writing notebook entries for almost a year, and whenever I wrote them, many people corrected them and gave me kind advice which I appreciate a lot. So,  I started to think that I could do the same thing in return for people who are learning Japanese, so I tried to. However, I found it very difficult for me to do that mainly for two reasons. First, it's difficult because I can't understand what the writers wanted to say due to the weird grammar which Japanese people don't normally use. I realized how much I usually rely on the grammar to read the passages. Second, I think one of the most difficult parts of Japanese to learn for non-native speakers is that there are three different kind of alphabets: Hiragana, Katakana and Kanji(Chinese characters). Native speakers can use these naturally as they grow up speaking and writing it. Many people who aren't used to mixing them make mistakes such as using only Hiragana, which makes sentences hard to read. After all, I'm not a professional teacher so I gave up correcting notebook entries. I'm searching for another way to be of help to Japanese learners right now.

*** Pretty good. Look up subjunctive mood and try to learn it. It would have greatly assisted you in this passage. :)

Do Hackathons Work for Something?

Recently, I went to my first Hackathon. For those of you who do not now what a Hackathon is, it [recommended: is an event that] can occur over a couple of days with a lot of coffee and pizza and people from different fields work together to achieve a goal.
My question after these two days was if all of the hours without sleep and all of the coffee and pizza actually did make a difference in the lives of the people around me, or it was just an experience for me and the rest of the people in the Hackathon.
The first objective of a Hackathon is to make students apply all the theory [they know] to the real world, but there is a second objective, which is change the world to a better place.
A problem arises when a corporation organises it. From this, the goal to be achieved is a goal that the company wants to be solved, so that they could make a profit.
I think the best thing about these meetings is the people you meet.  You can collaborate in the future.
Also, I think that two days are not enough. Some projects needs more time. In the two days most of them can initiated, but in order to achieve something, they need more time and the help of the organization.

*** I would recommend shortening your sentences. Many of these sentences were too long, and there were many errors as a result. Simpler sentences are easier to produce, and convey your meaning just as well. 

Kotatsu

MI's weather is strange.
Last week, I thought spring had arrived.
This is because the temperature was warm, and a goose was sunbathing near a pond.
But, yesterday and today were too cold.
So, I curled myself up under a kotatsu.
I have heard that people in Turkey have likely used kotatsu.
Is this true? I want to research this.

*** Work a bit more on past tense. This entire piece took place in the past, but you used present tense for most of it. 

Why You Should Visit the Black Forest?

The Black Forest is one of Germany's most visited places. This forest is located in the southwest of the federal state Baden-Württemberg. It's really beautiful there, and it has a lot of firs, valleys, mountains and some small lakes. It's also famous for the traditional "kuckucks" watch and, of course, the Black Forest Pie. This area is also known as great place for skiing. In particular, the Swiss love to visit the nearby mountain "Feldberg" in the Black Forest because it isn't far away from the border and a daily skiing ticket as well as (better: plus) the food are much cheaper than they are in Switzerland. In summer, the Black Forest offers you a big area for hiking and cycling. In the north, you can walk through its national park, which is called the "Naturpark Schwarzwald".

Please correct my text about my sightseeing trip.

*** Very good. The two biggest mistakes were actually quite minor in the grand scheme of things:

1) There were a couple of run-on sentences. To avoid this, it's best practice to break the longer sentences into smaller ones. 

2) Capitalisation: keep this consistent throughout your piece. You should always capitalise proper nouns (such as the Black Forest). I would also recommend capitalising all parts of the title except for the articles, but this isn't really an issue in iTalki I suppose. 

Hopefully I get to visit someday, this is one of the places in Germany I haven't had the opportunity to visit yet. :)

My Interests

I love contact sports. I have practiced kickboxing, boxeo, mma and jiu-jitsu. Although, I don't have a lot of time for practice because of work.

I always have a good book at my nightstand and go to the all of the concerts that I can.

Sports and food (e.g. cooking and eating) is what I like more.

I always love to visit other cities, but not like the typical tourist. I love to stay for weeks or several days in a city and to learn its history and traditions.

*** There were several mistakes in this passage for simple present tense endings. Try to simplify your sentences so that the subject is clear. Also, always state the subject so it's obvious what is doing the action.