Plenty, quite a lot, more than sufficient, rather a lot. Depending on the item some translations wouldn't work as well, for instance 'several'.
"Ho parecchie macchine" would translate well for most people as "I have several cars".
"Ho parecchi cappelli" would not translate well for most people as "I have several hairs"!
I have had some difficulty working out the right translation for parecchi-o-e etc too, but I think that you just pick the expression that fits the context, the common element being that they all mean more than just a small number - several, a lot, much, quite a few, quite some etc but if it is only a small number, a very few or some then use something like alcuni, qualche, pochi, un paio etc. Duo might not always approve all possible translations so you would need to report any that you know are correct but are not accepted. The easiest way to avoid this confusion and effort is to look at the first hint and take that one provided it looks correct, as I think most of the problems come from Duo only accepting a few of the possible translations for any given exercise.
Usually Duo allows one character to be wrong provided that the error does not create another valid word, as in the latter case it thinks you have put the wrong word rather than just made a typo. A missing character can count as wrong. Two wrong characters is counted as wrong. Accents and capitalization are usually not required.