T++'s answer about that is quite clear:But yeah, typically you just need to press "batch translation" (right of 'import project'), choose a column (like 'machine translation') and you're all set (to now refine every line, that is).
If you're using translate.google, T++ automatically creates batches of text that are sent every 5s, to avoid ban issues. You can get crazy times there - I've had 10+ hours for
dolls 
and other games with a similar amount of sweat, work and love poured in them.
You'll likely run into further issues with pre-MV games, like Lust Grimm, and you'll probably need to check out Scripts (and often CommonEvents). The relevant RPGM editor and/or a tool like Gemini will then be required if you're aiming for 100% English.