Hello Gerald
I am interested in WW1 but really no expert.
My idea for Bulgarians came from the combination of peaked caps and tight trousers.
But the more I look at the mould, I think, you are right.
And the Bulgarians had no stripes on the trousers (if These are stripes)
The Schutztruppe had.
British soldiers had wider trousers I think.
Greetings from a cold Austria.
Gerhard