Last of my digression here, then we can return to OP's question. Tobus, yes thankfully the word hasn't been mangled quite that badly. I do think that whenever possible we should use the correct word, spelled correctly, when importing words.
Example: Muenchen is the correct alternative spelling for the city English speakers know as Munich. The 'ue' are allowed under German language conventions in place of u with umlauts (the two dots over the letter). So for English speakers there is no reason to spell or pronounce wrong in this day and age. The only reasonable exceptions I can think of off hand are alphabets like Cyrillic, Arabic, or Cantonese.
It do understand completely the desire of the Welsh or anyone else to make the kilt their own. But the first generation of Welsh kilt wearers is still alive! The Irish have been wearing kilts for about a hundred years, max. It is an imported cultural item. It is not a longstanding and ancient tradition in those lands. Throughout the entirety of their wearing the kilt, the English, Irish, Welsh, Manx, Australian, American, Canadian, Jamaican, and South African people have spoken English.

That brings up point number two. Should we instead promote the term FEILEADH as the correct and propper word? It is after all the root word for the Belted Plaid (Breacan an Feileadh), Great Kilt (Feileadh Mhor) and Small Kilt (Feileadh Beag). Plaid itself seems to have been redefined as a tartan garment worn off the shoulder. Let's leave that on there for now out of simplifying our discussions. It should also be able to be properly spelled in all the Celtic, Anglo, Norman, Germanic and Romantic alphabets. I think that covers everyone in the Western World.
This has been a ranting blowhard special action report, now back to our regularly scheduled programming.