I understand that まぐわう essentially refers to the act of sex. But I'm trying to get some idea of the connotation. In Yofukashi no Uta, it's translated/localized as "copulate", which has a very scientific connotation in English, as well as the connotation of producing offspring being the ultimate goal. It's also rarely applied to humans in any normal conversation. Is that roughly on point?
To contrast with this: to my knowledge, エッチ, だく, and セックス are much more "commonly" used with a personable connotation, and やる being used more akin to "fuck"'s connotation in English.
Sorry if such "nsfw" questions aren't allowed here @.@.
If it provides some context: a pretty vampire japanese nee-san was referring to sex between humans with まぐわう, and a 14-yo boy was getting flustered by the usage of that term, asking why she insisted on using it in particular.