In fact the ancient Greeks didn't test out their theories at all, it was all philosophical, and they exchanged their ideas to each and discussed about it without hardly ever putting it into practis.Every genius made his own discovery on his OWN, Tesla never asked on forums...
Anyways... back to the point...
I would suggest you test if the 'Gloves of Haste' item ability bugs out.
Another way, there are other abilities to add attack speed that don't bug out at higher ranks right? There's always Endurance aura, and if you don't want a buff to show I remember the 'Tornado (slow)' ability to be able to increase movement speed without adding a buff, so you could check if it can add attack speed as well.
If none of the above works, I guess you'll have no other choise but to get multiple copies of the same ability for every % of haste in your system, though I'm sure there has to be a better way.
Also, very sorry but:
this looks like someone who's trying to speak English but...~