"easy to borrow" (as you say it) is not a thing at IB. So the one that posts misinformation is you. (Surely some other brokers use terms as HTB to charge more fees.)
No, I'm saying the borrowing works the same. So the market where the borrowing fee for the warrant is determined is the same as with stocks.
If you're short these ones you would see them back in your borrowing fee report section, just like any other stock.