Barriers are not buffs, I don't think it evens remove the stat boost component as that's also not a buff, but rather an aura--the fact that an overriding barrier can remove it is a clear sign, buffs have a clear start and end and, buff removal ability like sand dust aside, will run its course. To have something that doesn't remove buff to be able to remove/deactivate a boost, that boost is not a buff.

I think Healing Tip is an aura. The distinction between aura and buff is that aura is never distinctly cast at the start of the battle. Another difference is that aura have no expiration time whereas buff usually wears off at some points, most common being 3 and 5 rounds thou some less (fairly sure none last over 5). Note I say I "think" Healing Tip is an aura is because I'm not sure if it is one, I know there are auras (as opposed to buffs) in the game, I'm just not 100% sure which ones are.

For Kimimaro, last I heard, it removes the stat gained from the abilities but not the ability themselves because... well... they are not buffs, cursed seal create buff but is not buff, so it can stack back up. Like aura, you can tell if something is a buff by seeing if it is ever "applied" at any given time. If it is applied either actively via casting(include start of round) or passively as a response to some trigger(like the curse seal stat boost), then it is buff. But if it is never applied, it is not a buff.

I do consider not removing the extra attack bit of the lightning armor a bug thou, I don't see how that can not be a buff.

I'd say the barriers themselves are not buffs, mostly due to the fact that it can overriden by enemy barriers. I haven't seen any buff that behaves that way in any game.
That said, the stat boost provided by the barrier may or may not be buffs, it could be an aura of the barrier or a buff. This depends on a few things:
1. if the barrier is broken (in any way or form), does the stat boost remain(until its own expiration that is)? If it remains, it is a buff, otherwise it should be an aura provided by the barrier.
2. The clone bit you shown. Frankly, not every boost is displayed by the game, so it's hard to say whether the clone is or is not boosted. If it isn't boosted, then the thing should be a buff, if it is boosted but not shown, it is part of an aura.
Now, in theory #1 and #2 should be consistent with each other (either a buff or not) but... well... it might not be. And if it's not, I honestly don't really know whether it is a buff.

In another note I'm also not entirely sure what the categorization of hinata's passive is. Specifically, her passive doesn't give a triggered boost persay, but a condition boost where the bonus is based on her current health. If the bonus isn't considered a buff, all is well (thou that also show a stat gain animation like the barrier, stat gain thingy might have nothing to do with if it's a buff). If the bonus is considered a buff then... well... if it is removed when hinata is at 50% health, she loses another 10%, what amount of bonus def/res would she get? The amount equal to 10% lost health? 60% lost health? What if she is healed? What if she is healed and then damaged again? Personally, I think it would be easier to code and categorize as a self-aura type of thing but... yeah.. fun stuff to think about. (regular naruto have similar ability as well, and I think a few others. They are different from cursed seal as it's not stat gain per hit/trigger but based on current health)

What happens if you sand dust a lightning armor twice?
If you say the immunity is the thing that gets removed while protecting the others, if the immunity is gone, can the rest be removed after the immunity is gone?

3 v 3.... it does happen you know...

needs be tested... needs to find 2 pals for dis

What the heck is an "action".
What is its characteristics? What other "actions" are there?