Kasas can be blocked from accessing the Internet, so that you only have control through openHAB. If you do that, then there’s no real need to update firmware (assuming they’re working fine).
I don’t have any HS110s, but my HS105s are on 1.5.6 firmware, with no updates available. Also, I don’t recall them ever auto-updating in the past. It’s interesting that the HS110s are different.