Yes, it's been a problem for me too. Trying to ranged-attack an enemy, quickly enough that I didn't notice I was accidentally attacking the myrm, but visually it looked obvious my cursor was far enough away from the myrm as to not be targeting it
I wouldn't even think the game uses hitboxes since combat is just based on distance and your roll + bonuses vs their AC+bonuses.
I didn't notice for clicking on them since I use a controller, I can just cycle targets with the d-pad. The cursor selection is kinda borked in general, and I don't know if that's a controller UI issue or global.