(My bolding) - one might almost say, Welsh vowels (and consonants) have rules; whereas English... By my understanding, Welsh spelling-vis-a-vis pronunciation is reliably phonetic: learn the rules (which strike 100%-English, no-Welsh-language-background me, as not all that daunting) and you'll know how to pronounce words / names. Whereas in England - and it rather seems, also Scotland - pretty well "anything goes".
Gaelic does have reliable phonetic rules. It's just that they're really complicated and also have very little in common with any conventions in English.
In Scotland you also have a lot of place names that have been butchered by being spelt half in English by people who were no good at spelling either language, especially around the populous bits, and similarly with disturbances that originate with the Vikings or other historical invaders. And in South Wales or near the border you get place names that use a mixture of Welsh and English vowel mappings in the same word, or that from the look of them could be using either mapping but you don't know which.
As above: I'm not Welsh and don't claim learned scholarship; but I'd reckon, "Glun-duvr-doo-uh (or perhaps '-ee')" - the "u" 's in the first two syllables, as in "glum".
Y in Welsh is a bit of a bugger because the commonly-stated rule of "it's Y at the end of a word but U earlier in the word" ignores the existence of all the awkward cases. In the German-style compound words you tend to have to reset the rule at the beginning of each sub-unit. And it's O in some cases, like Hywel ("How-el") and Tywyn.
I'd pronounce that "Glin-dover-dwee", more or less, with "dover" as in "pigeoner" rather than like a Channel port.
