Sorry for being vague mate! I was referring to regular jumps, though the walljumps may be imprecise due to how fast the player is during a walljump. Horizontal movement during jumps, and moving in general, should have at least a few frames of momentum until you reach max speed. Maybe I just had bad coordination today, but making small jumps from one block to the next could lead to me overshooting or undershooting just a tiny bit.
I think if you slow the jump and wallslide down a little, and add a little bit of momentum to horizontal movement, your game will feel perfectly fine. I noticed it was made in GMS2, so I would recommend using an Approach script for horizontal speed as a super quick fix.
Thanks again for clearing it up! I was afraid to add too much momentum/too little friction to the game and instead focus on near-immediate starts/stops so that the movements feel more "precise". It seems like a few people mentioned this however as making the game feel just the opposite though -- imprecise. So I'll play around with the different settings and see if I can make something that feels a bit better. Thanks for the script suggestion!