Another recent example is when Israel withdrew from Lebanon in 2000 to UN sanctioned, internationally-recognized borders.
Israel hasn't been limited to its UN sanctioned, internationally-recognized borders since 1948. The pre-1967 borders include territory annexed in previous military conquests. Not just Shebaa farms, but also a little town called Jerusalem. The UN certified in 2000 that Israel had complied with Resolution 425, which did not have the explicit requirement of a withdrawal to its original legal borders, but merely from newly-annexed territory. Of course, all these "details" just don't agree with your "facts on the ground", so it's best that we leave them swept under the rug. That Shebaa farms was "never part of lebanon", as you say, shouldn't have anything to do with this, since it was a part of Syria, and sure as shit not a part of Israel. But I guess it should be okay for Israel to annex Syrian territory, because it's not Lebanese? I suppose it wouldn't have been a problem if the US just annexed Iran after we went into Iraq, since we'd still be withdrawn from Iraq, right?
The agreement in question dealt exclusively with Lebanese territory. Not Syrian, Jordanian, Egyptian or any other country. There are plenty of countries in the Middle-East that make up conflicts on a monthly basis that have no grounding in fact. So long as Arabs are slaughtering Arabs in the Middle-East, even within their own countries, I think it is safe to say the probability of an Muslim-Jewish peace is very low (if they can't even get along with themselves, how can we expect them to play nice with others?)
Hezbollah is a Lebanese organization, not Syrian. As such, they have no legitimacy in demanding the return of the Sheba Farms region to Lebanon. This territory was never part of Lebanon and Israel is fully in the right according to international law in that it withdrew 100% from Lebanon. Syria is more than welcome to restart peace negotiations with Israel if it so wishes. Please don't open up this discussion to other conflicts, as this is a separate discussion.
The fact of the matter is: the International Community made political and military guarantees with respect to Israel's withdrawal from Lebanon, and it failed to adhere to them. The same is true in the case of Ukraine. Had Ukraine kept their nuclear weapons you can be sure Russia would not have invaded.