As a non-native English speaker, this is what I thought when I was first introduced to this word. I was even fighting it when I was told it meant "every two weeks". Then I caved and went with the flow. You are the first person to ever agree with me. I'm not crazy. Thank you.
You might already know but English has the word 'fortnight', which also means every two weeks. In the UK, I've never heard 'biweekly', so you might find 'fortnight' easier to use.
I actually didn't know that one, even though we were taught British English in my country. All I know is that annoying video game fortnite. Lol
But now I know, thank you :)
My advice for non-native english speakers: words are made up, they mean whatever people agree they mean.
It doesn't really matter what the dictionary says, except as a general guide. What really matters is what the person you are talking to thinks it means. We are really just trying to communicate.