Don't feel bad. If they're still using the standard for Jin Bao euph case strap set-up, you're only one in a long line of those it's driven crazy. When I got my Mack Brass euph, I tried to put the straps on it and just couldn't handle it. I got a gig bag with reasonable straps (which was a better idea anyway). I don't know what it is about the Chinese line of euph cases/bags. All of the other instruments have straps that seem to make sense.
Gary Merrill
Wessex EEb Bass tuba (DW 3XL or 2XL)
Mack Brass Compensating Euph (DE N106, Euph J, J9 euph)
Amati Oval Euph (DE 104, Euph J, J6 euph)
1924 Buescher 3-valve Eb tuba (with std US receiver), Kelly 25
Schiller American Heritage 7B clone bass trombone (DE LB K/K10/112/14 Lexan, Brass Ark MV50R)
1947 Olds "Standard" trombone (Olds #3)