It might be possible to add. I think it'd be tricky for a few reasons (mostly that caches are sorted by a mixture of build/timestamp, some caches lack one or both of those fields, and it might be tricky to write an SQL query to do this efficiently). But I'll add it to my list of possible ideas cos it would definitely be useful.
Edit: thinking a bit more, perhaps it could be based on the file version rather than the cache build/timestamp, given the file versions will always be present. Though the fact that OSRS diverges from mainline RS after 468 might complicated things...
Edit 2: Desetude provided a few more XTEA keys for mainline RS.