"Serbian - српски" and "Serbian - srpskohrvatski" spellcheck dictionaries don't load in Edge Canary version 81.0.370.0 and Dev version 81.0.361.9.
Languages load in Beta Channel version 79.0.309.54. This may be related to change made in Chromium Beta 80.*.*, where respective dictionaries were updated from version 3 to 4:
sh-3-0.bdic -> sh-4-0.bdicsr-3-0.bdic -> sr-4-0.bdic
@msmiljanic Thanks for letting us know! I'll share this with our product team and loop back with you if they have any additional insights.
Fawkes (they/them)Project & Community Manager - Microsoft Edge