Not my experience (English - Somerset based - with quite a lot of work and friends the other side of the bridges). If you show some respect towards others, I generally find it returned. They are also not users but speakers. The only time I find dual language to be a bit of a pain is in lifts: being told the doors are closing in two languages is bloody stupid.
and want to deny that Welsh counties were annexed in to England and want to try and hold back the tide wrt English language use in preference to Cymraeg.
You might want to reread your history books and concentrate around 1066. The Norsemen didn't really give a shit whether you were "welsh" or "english" (neither of which, as we now know them, really existed as such at the time). You were probably a vassel, whatever language you spoke. I can't remember or even be bothered to look up when the concept of county was created. I think we still had hides and hundreds back then.
Re counties, there were established principalities in the West of the British mainland -- Gwynedd managed to subdue many of these other counties (ie independently governed areas), whilst paying fealty/homage to the English Crown, once Gwynedd had subdued Deheubarth and Powys and such, they (Llewellyn The Last) stopped paying the Crown. At which point Gwynedd was put down, handing their recent won territories over to be annexed to the "English" King's territories (Edward I).
I don't think the Welsh counties in general were divided in to hundreds until Henry Tudor (who also issued a writ demanding use of English across his whole territory). Hides and hundreds, like the words, are Anglo-Saxon I think?
AFAICT Gwynedd grew strong (post-Romans) by earlier conquest by Vikings and Irish-Scots.
You're right, the Norse, like the Romans before them didn't care what tribe you hung with, Wales is called that because it's the bit the Romans hadn't conquered yet (cf Walloons, Wallachia (? in Romania)); which is down to physical geography. Same with the Norse AFAICT. And the same in the other direction with why Gwynedd was able to conquer the principalities but not subdue the Marches or Pembrokeshire.
https://en.wikipedia.org/wiki/112_(emergency_telephone_numbe...
We get silly things in Wales like Cymraeg mono-lingual government announcements/adverts on the radio (accessible to about 7% [1] of the population vs c.100% if they were in English), motorway signs that are only in Cwmraeg for half the people passing them (they change over, useless if you passed already), travel announcements in Cymraeg first. Heck, if you ring 999 in an emergency you have to wait for the Cymraeg speaker to finish their 20s message before you start your call.
Welsh people use British-English language predominantly; the Welsh name is the name in English, the Cymraeg name sometimes differs.
[1] roughly: ~15% of the adult population say they know any Cymraeg, half of those are fluent (self reported). FWIW half of those fluent say they prefer to use English. So one could argue you're catering to <4% of the population.