Loth to restart discussions passim about manufactured tradition, but my impression of a lot of "regional" English (and other) tune books is that the tunes come in a number of categories:

Tunes in an identifiable style that seems to be genuinely peculiar to the area- many Northumbrian pipe tunes and Lancashire/ Cheshire 3/2 hornpipes are examples of these.

Tunes which are common repertoire but have a regional twist to them. again the Northumbrian tradition is a goldmine here, along with tunes like the 3/2 hornpipe version of the Foxhunters Jig (no arguments about which was the "original" please).

Tunes which were probably of local origin, but not particular to the local tradition- the sort of thing composed for respectable early/mid 19th century dances.

Modern compositions which sometimes seem to have little in common with the tunes of the first category. Many recent 3/2 hornpipes I've heard seem to have quite a different character from the old ones- probably due to different instrumentation (e.g. box rather than bagpipe) which doesn't have the same range limitations, different characteristic periods, use of chromatics etc. Note that I'm not saying they are bad, bogus, intrusive or anything- just that they are different. To me they often sound French.

I quite agree about there often being more differences than common ground in traditions, but wonder how much of that is a real reflection of the whole music of the regions.