Technically,... she's not "eating" chains... she's stretching them...
If she was eating them, your sprockets would chew up...
If your chain is too loose,... it can get whipped around and jerked about,.. causing faster stretch...
... but, it sounds like you are being meticulous with your adjustment, so I don't think that's a factor...
It's just stretching...
Is your chain a #520, or #530?...
Hard to believe a little 30hp bike would need a #530 chain,.. but...
...
This is why I like the belt... a #530 chain will add a lot of unsprung weight,.. and if it's an o-ring chain, it will steal about 1/2 a hp or more with friction...
Maybe you should consider the Kawa front pulley mod and stay with the belt?....