I have 2 suggestions
First: Making a help file in japanese (i loose hours and hours to explain them how to use renoise, since i played there they all want to compose with this and they really don t speak english well, worse than me!) italian, french, spanish (other countries speaks quite good english)
Second: I can’t see slavian characters in my sample library, i have little squares instead of the “specials” č, ĕ, ř, ¨, ů… can i solve it myself?
Probably that depends on the OS settings. I can see the slavic letters fine, but I get some strange letters for italian letters with accents.
Try this on for size:
http://reg.s63.xrea.com/
Yeaaaaah thank you dblue!!! you can t imagine how it please me 
all my softwares works perfectly with slavic letters but not renoise 
while we´re at it… I could imagine localized renoise versions. Well, language files and stuff.
Face it, there are actually many ppl, who just drop a program, because they aren´t capable of some proper english (though renoise ain´t this hard).
I found that especially us germans are somehow mostly not really into other languages. Business, daily life… doesn´t matter. 
Well, atleast I think this would extend the userbase too.
Maybe renoise users from different countries can help to build tutorials in different languages, but there will be no need for many languages as mat-weasel said, just those languages which are widely spoken might be enough.
good idea, i could translate renoise help to czech l. and mat-weasel could maybe help me 
More languages would be lovely but how many people would be dedicated to keep the pages updated with each new release.
As for now, the Italian edition (which is being translated in the background) is not going very fast.
There is this problem where we can’t guarantee multi-language documentation simply because this plan would have to rely on a lot of people at which in the end most will drop out sooner or later.
If you don’t have much spare time to spend then it won’t be wise to offer help on the project either.
Another problem is the grammar of foreign languages which we can’t check.
reasonable.