5 sentences with new vocabulary (please, correct me if there are any mistakes)

New words: to conduct, to adhere, comprehension, poor (=bad), notion (=idea), prosperity, tempting, to remain

1) From now on our company won't conduct business with that individual manufacturer because he didn't adhere to an agreement that we had made in a year previous. (You used the time backtracking modal "had.")
2) While reading in English some students try to translate every single word into their first language to achieve a comprehension of the text, but that is not always necessary.  (More direct referencing is needed here.)
3) Because of poor vocabulary I had no notion what they were talking about, so we had to ask for the help of an interpreter. (PERFECT: GREAT JOB!)
4) Our company is still very young and, of course, income is not big right now, but we need to keep working hard for the future prosperity of our business.  ("The" is needed when meaning general or categorical with an ideal.)
5) Your offer to go out tonight sounds very tempting, but unfortunately I feel a little bit sick today, so I'd better remain at home. (Either "to" + base/infinitive-form verb or inf. verb + "ing" are okay. But don't mix the two.)