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. :/