Plural of "copula", does "copulas" or "copulae" sound more professional?
Solution 1:
As a native British English speaker, to my eye "copulae" would be the most professional-looking.
Solution 2:
It’s not a common word, so it’s unsurprising that searches in the OED, COCA and BNC are inconclusive, with two records of copulas in the OED and one in COCA and none at all for copulae. My own preference is always for the English over the Latin plural, unless there are compelling reasons to use the latter. In practice, the plural will seldom be required at all, and, when it is, there's always the alternative copular verbs.