I have noticed a bug with accomplishing getting Elly's gun in the cathedral in that the game starts to lag and makes it almost impossible to complete the task without getting caught. Also in my last go around (version 11.06 or 11.16) this lag also occurred in Lielle's dungeon in two areas. One was in the red blue puzzle area and the other is the first secret room where you race vs a flame. Again the lag makes beating these areas almost impossible or in the vs flame room actually impossible. The rest of game works fine and there is no lag when you leave those areas, it only occurs there. 

yeah i got that bug too

I have confirmed it still occurs in Lielle's dungeon in the red blue puzzle area. However, the problem appears to have improved[But not gone away completely] in the vs flame room (I was able to get the treasure).