Hi, Rich. I had a look. You really do have some wacky things going on in there!
I didn't actually find any strata steepness set above 0.25 in the file. I did find lots of fractals that won't be doing what you expect them to, though. There are at least 4 or 5 power fractals that have far larger 'smallest scale' than they should to make them work 'properly', you should never have a larger 'smallest scale' than 'feature scale', let alone larger than the 'lead-in scale'!
Lead-in scale = largest number, feature scale = middle number(or, equal to largest), smallest = smallest number(or, at least never exceeding feature scale). You could even have all scales the same without running into confusion and the fractal will do what you think it should be doing. When you get into mixing extremely widespread scales and sometimes laid out in a backwards order(like smallest scale exceeding lead-in etc.) well, I'm not sure it would cause 'errors', as such, but the fractal
certainly won't be doing what you think it's meant to be doing.
There's also some nodes in there applying really HUGE amounts of displacement, especially in comparison to the scales they are displacing by.
I tried to play around with it a little but the network is extremely complicated,
far more so than I think it needs to be for the image you're trying to make, by the looks of your previews.
Eventually, I completely broke it and lost the entire look of the scene just by trying to tidy up node scales and put things in the right order!
My advice would be to start afresh from a default project and add just one shader at a time to apply each aspect and feature you want to achieve. First, a nice steep fractal, work with it until you get a form you like as a base, next add any more detail-adding fractals/strata settings/redirects/etc. but try and get the most out of every single node you put in there to ultimately use as little nodes as possible to reach your goal. I think you could get similar, if not better, results than your preview render, and possibly by not even using
1/10th the number of nodes as are in the .tgd you posted.
Maybe you just have a better grip on multi-tasking than I do but to try and control all those nodes drove me very quickly insane! I do make some pretty wacky things with TG myself sometimes, things that look like they might be very complexed but actually are not at all and usually use relatively little nodes, I've never had a node network like this one!
Sorry I couldn't be any more help but I can say that those tears and holes in your terrain are
definitely coming from
really extreme settings, in multiple nodes. Good luck, phew!