OK, so if I understand it correctly, when it’s on the 11t at the back, a change from the inner 28t to the outer 42t ring results in the chain dropping outboard of the big ring? If this is the problem then I agree with recordacefromnew - it’s not due to the mismatch between an MTB crankset and a 130mm rear end.
A triple usually has a 45mm chainline on its middle ring and something like 49mm on its outer. The cluster on a 130mm rear is only 2.5mm further in than on a 135mm rear end. I think the chainline on a standard SRAM MTB double front is 49.5mm. So the cumulative offset inherent in your arrangement, compared with a matching 130mm road group , is only about 3mm, give or take.
Assuming the front mech is in fact a compatible match with the crankset and it looks right from the photos, it should be possible to trim the High position limit screw to prevent the chain dropping outboard of the big ring in any circumstances. Usually, the problem when this is done is that the chain rubs the inside of the cage when in big/11t top gear. In your case, with the chainrings a bit further out than normal, this problem should be less likely.
In fact, with it set up as you have it, I should have expected your problem to have been that if you set the front mech so it moves left enough to derail the chain onto the inner ring, it overthrows it to the inside of the ‘ring and if you set the inner limit screw to resist this, it doesn’t move far enough to get the chain off the big ring. In which case the usual remedy is to set the throw wide enough to work but then fit a robust chaincatcher to guide the chain onto the inner ring.
Or am I still on the wrong wavelength?
