Typing in the Devanagari script causes very unusual placement of vowels in relation to consonants. The correct place to put the vowels is always after the preceding consonant, but the VisualEditor causes very strange placement.
To try, I used the standard Hindi InScript keyboard (not ULS IME, but the operating system's InScript keyboard). I tried to type the word "अंग्रेज़ी" (the Hindi name of the English language).
To get that word with the InScript keyboard, type the following keys on the English-US keyboard:
The expected result is "अंग्रेज़ी".
The actual result on Firefox 22 is "अंग्ेच़ीर".
The actual result on Chrome 28 is "्रेची".
I tried this with Firefox 22 on Fedora 18.
I mark this as blocker, because in this state the VisualEditor must not be widely deployed on a Wikipedia that uses the Devanagari script, such as Hindi (hi), Marathi (mr), Nepali (ne) or Sanskrit (sa) (there are a few more languages that use it). It's OK to have it as opt-in for testing on these wikis, though.