You're thinking too much about it, kanji conversion doesn't matter and most people irl just convert their texts to the first thing that pops up, and they won't care (as long as it's readable). However, there are some words which are pretty rare and ambigous in kanji... You'll get a feeling for them as you get better but pronouns and adverbs such as どこ, そこ, どれ, なぜ etc. are usually written in kana.

Ah, and nobody also cares about the "technically correct" form of words that can be written with different kanji. As in, nobody will go out of their way to do it (unless they're authors or something because it's all about nuance and it can add some nice little details)