I have a weird situation where I want to develop Artillery, but it's locked behind Howitzer Mk2, but Howitzer Mk2 is permanently unavailable despite all two of its requirements being already researched: Howitzer Manufacture, and Military. I think the tech tree is broken/missing something?
I am unable to reproduce this behavior on my side, would you be able to send me more info regarding your save game? This is most likely a strange interaction with another mod that modifies the name of the Shooting Speed technology but I can't be sure without more info on your game.
You can dm me on discord at Volvary#6909 for a faster reply.