I'd like to address a few things with the acidic archvines found in the Nether, and would be happy to split this into multiple issues if preferred.

The acidic archvines in the Nether currently make surviving there impossible. You need to bring at least one item from the overworld (leaves, as well as iron for shears to obtain them), meaning any survival players trying to start in the Nether will be completely halted from progress, unless they stay hidden inside walls.
My first suggestion here is to provide an alternative Nether-based recipe for the plant hat (possibly substituting leaves for the mushroom tops found in crimson and warped forest biomes.

Additionally, the range of these creatures seems a bit far, as they are able to pull you all the way to the ceiling of a large open area, which spells certain death in most cases. Perhaps a range of 16 blocks or so would be fair, combined with some kind of sound or particles coming from the creature to help locate it before you're too close.

My next suggestion would be to allow countering these creatures in some way; possibly by having the tongue be a projectile that strikes at you with an audible cue to grab you, so that you might punch or shield from it. It would also help to be able to cut yourself free from the vine while it's pulling you to it, potentially by using a sword.
Some telegraphs could help the experience too, by having a sound and visual as it latches onto you, allowing a brief window to escape from it before you're pulled up.
These changes would make it reasonably effective to counter the archvines, as currently the moment you're lifted off the ground, you are as good as dead.

Thank you for your time, I hope some of these suggestions make it into the mod, as it is otherwise a delight to play with.

I like the ideas, I think I will add them in the future, but currently I do not have time to work on the mod.

Incase this gets revisited in the future, I'd just like to add an extra suggestion: given the changes coming in the next Minecraft version; it may be an extra nice touch to have these creatures react to sounds rather than line of sight, the challenge would then be to try to stay silent around them.