Awe, Alexander, you did it again. I understood a lot from your again-great posts. If I may ask a question in your thread, Stephen?
Can we tell from the build type
https://en.wikipedia.org/wiki/Eyepiece#Eyepiece_designs which EP is designed for correcting concave (Newts) and which convex (refr., CS, Mak)?
For example, if a lens design ends with a concave one nearest the eye-end, it'll correct best in a newt? Or vice versa, a lens design ending with a convex will best correct in a newt?
Will a barlow mitigate or amplify the eyepiece design mismatch in a newton?