I have a pair of T1s and I don't particularly have any problems with them derailing. My main line curves are 34" or greater radius and turnouts on the main are #10, however, the T1s have no problems on my turnouts as low as #6 code 83 Shinohara.
Most of my main line curves are superelevated with the outer rail .040" above the inner rail. The transition is very critical.
One tool that I have used to "fine-tune" the track elevation is a flexible plastic ruler/straight edge. I have one that is 16" long but a 12" will do.
It may require the help of an other person but with the straight edge directly on the rail-head you can curve it to follow the track geometry. With good back-lighting you can observe any dips or raised areas. As careful as I could be when laying track, over the years there have been places where a high spot or low spot has developed. By observing the gap or "bump" where the straight edge meets the rail you can observe what corrective action may need to be taken.
I have corrected high spots by warming the rail with a 35 W. soldering iron and when the ties get soft press the rail down with a 6" or so steel straight edge.
A low spot is a little trickier if you have ballast but you can wet the ballast enough to get a tool, I have a mini-tack puller but a small screw driver could work, too, then raise the low spot and shim it until the ballast glue sets again or the shim is held in place.
Another handy tool is one of the small digital levels available. These can be run along your track to locate any side-to-side elevation problems.
I found mine on Amazon, there are others available.
I had to make some corrections recently when I recieved the Broadway Limited P70 coaches. These cars have NO forgiveness in the lateral play! I have made several attempts at freeing the trucks but they will require a little more work.
Still, there were two places in my track work that these cars found and they didn't like the condition. Sure enough, one was at a place where the superelevation transition was just a little too much of a drop. A few carefully placed .010" shims took care of the issue.
Good Luck, Ed