In this post, @Brian_Roland said that Opus VST3 does not work with Dorico but Opus VST2 does work when bridged via Bidule (at extra expense).
If you create a test project in which the women’s or men’s voices sing the same vowel sound at every possible pitch, I suspect that some pitches will sound noticeably louder than others; this is where the perceived accents are coming from.
I have encountered this problem on rare occasions, usually when a syllable begins with too many consonants.