Maybe l could also add my ha’penny worth, based on personal experience.
l had a failed marriage in Thailand and obtained a divorce some years later via a Thai Court, retrieving my assets in the process. The divorce wasn’t registered in the UK, in fact I’m pretty sure it wouldn’t have been possible anyway, maybe you could enlighten me as to which UK authorities you refer to.
I met someone else and we’re in our 18th year together, as girlfriend and spouse, during which time she successfully applied for numerous visas to the UK, as my girlfriend when l was still married to the previous lass, and as my wife following our marriage, there was never a problem due to me still being married to someone else, for visit visas and ultimately, some years after our marriage, a settlement visa.
For her settlement visa l, as her sponsor, submitted a copy of the court order in respect of my divorce along with a translation, her visa was issued without further question.
So in my experience the lack of a divorce being registered in the UK, to whoever, didn’t make anny applications “non-starters”.