Yeah the trenchgun was bugged (and other guns to lesser degree too) I released a new fixed version 1.2. Check it out. Trenchgun should work now. And also ammo should deplete in-battles too in a correct way. The sprite switch bug with your main character happens because there was a trigger in the tunnels that caused the game to recognize occultist as the main character in some scenes. I removed that trigger too, so hopefully it won't happen again. For Kalev, it's just a bug. I need to handle that one for the next version.
Thanks for letting me know!