I’m not exactly sure what your point is... I guess you already know that a transitive verb requires an agent to complete the verb, and it generally focuses on someone who does/did the action. Person は/が Object を Verb for example. So if your “action” means the object, you are right. The word order of Japanese is “subject - object – verb”, so the verb is basically at the end of a sentence except inversion. Sentence ending particles like “ね” or “よ” and etc, do come after the verb tho. As for your Japanese phrase, it’s a bit hard to understand without context. “マリアさんは、イタリアで日本語を習ってから(“place”へ)行きました“ is similar with your English sentence, so I can guess she is going to somewhere after learning Japanese. Adding a place to the sentence will help readers better understand in this case. Sorry if I misunderstood your question. :/

Yes, you are correct. "マリアさんはイタリアで日本語をならって行きました" means that Maria learned Japanese in Italy before going somewhere. "マリアさんはイタリアで日本語をならって来ました" means that Maria learned Japanese in Italy before coming (to the speaker). However, I would probably say "マリアさんはイタリアで日本語をならってから行きました" and "マリアさんはイタリアで日本語をならってから来ました". I am not sure about the grammatical explanations but adding "から" makes the time reference clearer. (lit. translation: After learning Japanese in Italy, Maria went somewhere./After learning Japanese in Italy, Maria came here.) But your examples are totally understandable and correct. Other examples... マリアさんはドアを開けて(から)行った。Maria opened the door before going. マリアさんはドアを開けて(から)来た。Maria opened the door before coming.