Ardy Achievement Diaries Thieving Bonus - Medium vs. Hard

I've had almost a straight split of people say the medium and hard thieving bonuses stack and don't stack. Medium says it gives 10% increased thieving rate in Ardy. Hard says 10% increased in all of Runescape.

Some people say "well that obviously means the bonus is limited to Ardy for the medium and then open to all of RS for the hard, resulting in a 10% bonus no matter what."

Others say "well that obviously means that you get 10% in Ardy for medium and since Ardy is in Runescape you get another 10% for hard."

I think trying to interpret the meaning is pointless. Does anyone have proof one way or the other?

 

I just got a response from Mod Ash, it doesn't stack.

https://twitter.com/JagexAsh/status/720247624004030465

 

Hurray! Thanks a bunch!