Canadian here, with 50 years in the workforce. I've never once been paid semi-weekly or bimonthly. Here, biweekly is every two weeks semi-monthly is every half month. Obviously, that latter is often spoken of as twice a month, which just adds to the confusion between "bi" and "semi".

The reality is that these words, like most words (at least in English), mean whatever the speaker wants them to mean and consensus can be hard to reach.

I give you the phrase "table the discussion". Sometimes it means to formally bring something up for discussion. Other times it means setting the discussion aside for future consideration.

Or, my favourite from my childhood, "fat chance" which means that something is even less likely than if it had a slim chance. Granted, that might be more in the line of idiomatic slang, but it stands as part of at least the era's Canadian English that did have broad consensus and still does, I think.