Ah, I see that. the only problem I can think of is that it'd bring your derailleur out by 5 mm or so, possibly making it impossible to reach your easiest gears.

EDIT: By the way, those problem solvers aren't meant to do what you want them to do. They're meant to be carried to replace all types of derailleur hangers on bikes equipped with a replaceable one (since they're often different shapes.) You may be able to do something by grinding parts of what's left away to try to fit a modern derailleur hanger on it (then screw the hanger on.) but it'll always be a bodge and on a frame like this, with such a limited lifespan, it's not worth it (in my opinion.)

If you REALLY want to fix it. Buy a derailleur hanger that looks like it'll sorta fit. Take the frame and hanger to a machinist and say "I want to mount this part to this part so that these holes line up without welding and/or heating."

Pay the man a few hundred dollars and viola, you'll have a ridable frame again. Or, take that few hundred dollars and go buy yourself another equivalent frame and transfer the parts over.

And apologies, I'm not sure where I got that this bike was a mountain bike... was it mentioned above perhaps?