Tinker's Construct Bug for 1.12.2

[ImStillDead]

Hey I happened to notice while playing with Tinker's Construct 1 big thing and one small thing, The bigger problem I'd like to get fixed if possible is some items like the longsword and slime launcher are for some reason only wielded left handed and I can't use their secondary actions, I found this odd because the rapier works beautifully. The second much smaller issue is Slime boots, While jumping off high ground if I hold jump to "Keep momentum" I loose all momentum and just jump from the ground no matter how High I fell from, but if I don't hold jump then sometimes will I keep my falling momentum and bounce (more often than not).