I think it's an english loanword, and therefore the pronunciation is english?
So as a loan-word, the indefinite plural would be "guider" and definite "guiderna"?
It's fine actually. A loanword that kept the spelling and pronunciation.
And futhermore - puts on the Swedish definite article "-n" at the end.
Rightly so! Many English loanwords 'Swedify' their spelling after some time, such as kex, keps and mejl from cakes, caps and mail respectively. "Guide" however, has been very resilient, and kept its spelling despite the test of time.
>kex from cakes
Which is funny because the English word cake itself derives from the Old Norse for cake, so ummm, I guess we finally returned our loanword?
To an extent- it sounds weird using RP, as the diphthong is too open (gaah for Swedish vs gahh for RP- sorry, don't know IPA). It works better with some Northern-England type accents, or even possibly some American accents. Unless it's just the TTS...
I don't hear anything weird, maybe it has been corrected? Your link has the pronounciation of 'guide', here duolingo includes the definite article -n