Thanks, guys. Same answers I get from Romanians. It's just hard for me to accept that they'd changed just half a pair of opposites.
Something I googled on "Dacia" about the language; that according to both Herodotus and Pliny, the Thracian language was a coarse form of Latin. The Dac, a Thracian tribe using similar language. The Romans occupied only 14% of Dacia, for only 150 years. The author questions whether that brought their language, or they spoke a form of Latin/Thracian already.