Sasaferrato
Super Refuser!
They'll have to make some fucking effort and get used to it. The age of English imperialism over naming is over.
This may indeed be so, however, no person can be compelled to call anything anything. To Anglophones, they will remain the Brecon Beacons.
I'm a Scot, with much more experience of non English place names, and I have difficulty with the pronunciation, heaven only knows what the section of the community that cannot pronounce 'loch' correctly will make of it. I suspect that to many in Wales, they will remain the Brecon Beacons.