When a pass2 rule reduces the number of Braille cells in the translation, the output positions are not updated and so the output positions array becomes wrong. In the worst case the output positions array can contain values which are invalid index values for the translation and so would lead to a crash/exception.

I have not tested this to see whether a pass2 rule which adds extra Braille cells also suffers from this bug, but at least in that case values in the output positions will still be valid index values for the translation and would not lead to a crash, it would just lead to incorrect mappings.