Even in a US-only work environment I sometimes use fortnight to avoid the awkward ambiguity of “bi-/semi-weekly”.
"Every other week" or "twice a week" is much more understood, even if it's a bit wordier. Fortnightly is nice if fortnight were a real word, not some made up british thing.
I found my frequent use of double negatives to be problematic and had to train myself to say "I'm good" instead of "Not bad".