You said typos and punctuation can get lost, but do you know if accent marks get picked up at all? I ask because the sub language is Italian, which is chock full of accented vowels. If it doesn't pick them up at all, it'd just be good to know from the get-go.
Accents are often a bit problematic too, yes. It goes like this: once you feed it the subs it asks you what is what as soon as it starts; it tries from the beginning to separate letters when he notices there's some space between two symbols, but sometimes that space is too small and it takes two or more letters together and you have to correct it. Anyway at first you have to tell it each time "this is a G, this is a R, this is an 'é' " and so on. Once he has in memory at least one entry for every letter it can encounter it can process the whole subtitle stream without further input by you. Accents and punctuation often confuse it because an accent might make it think it is actually more similar to another letter, a comma might get missed because it's small or with certain fonts confuse it into believing it's an apostrophe, a comma might be seen where there isn't one, suddenly it encounters an italicized line and it goes bonkers, things like that.
The more time you take at the beginning to manually give it information the more picky it's algorithm gets and the less errors it does, but you have to be patient and small symbols will often still give you troubles. I remember that when I did it with SubRip for a couple of eng subbed series I had to translate in Italian I ended up giving up on making it recognize apostrophes by themselves and just made it look for whole particles/common words (like it's, 'll, 'd, don't, can't etc): as those are relatively few and consistent in common English it made my life a lot easier as the software had much less freedom to be misled into confusing one thing for another. Italian isn't so convenient though with all those accents, or with how we use an apostrophe between the article and the subject whenever the latter is in the feminine, so it will likely give you some headaches. It's still way better than having to pause the video every 5 seconds...
BTW, as it happens you are actually translating from Italian (to English I assume?), should you have doubts about some lines feel free to give me a word, lately I'm more or less grounded at home due to health issues so I often swing by here with too much free time for my own good on my hands.
