Just found what caused the bug : it's a stupid text editor problem, I've made special seas garrisons in notepad iirc and cut and pasted the texts, and this kind of quotation marks � was used ; when most of the map made with wordpad use this one ".
(edit : lol the forum itself doesn't seem to make a difference, but the difference appears in the .map text, one kind of quotation mark uses a different symbol for beginning and end of quote, when the other only uses one)
And the soft seems unable to recognize all � (end of quote) as correct quotation marks.
Affected provinces are probably : 187, 279, 307, 335, 286, 214, 99, 23, 15, 13, 20, 14, 66, 106 (about all deep seas provinces of the underworld except the two in which I have changed the garrisons in previous version because I've found they were bugged and the ones with big monsters made in wordpad)
(seas garrisons out of deep seas and of central deep seas were seen bugged and changed in wordpad and so aren't concerned ; should have made a test with a sea nation conquering the caves/deep seas
)
ps : Gunsliger thanks a lot for the report