The syntax of REQUIRE_COMPONENT is
REQUIRE_COMPONENT modToUninstall modComponent String
and modComponent isn't documented, so you could have been right that it can be a LABEL, but in fact the WEIDU parser seems to insist that it's an integer.
Yeah, the documentation for a lot of the old features just kind of assumes you know the "types" of the arguments. As you've surmised, REQUIRE_COMPONENT requires that modComponent is an integer, whereas, say, REQUIRE_PREDICATE, evalutes a patch expression, which may be a string, an integer, or something like ID_OF_LABEL.
So, unless majority of modders want's to change how LABEL works and in which context is used, and wisp will introduce those changes, I'm gonna assume that my GUID/UUID request can't be solved via LABEL, right?
LABEL is not changing, no. Are the salient points of your UUID proposal still that they'd live in the global scope (alongside TP2 names, rather than under them, like LABEL), are added to the log and maybe that a component can have at most one UUID? If not, would you care to summarise the current status?