Adding to this, I have found, by accident (and poor aim), you can get away with a snip at substrate level and it will grow right back, assuming that the roots are established enough I suppose. Obviously, this is much slower growth than if you keep some leaves on :oops:
Without having read the entire thread, I will offer my (limited) experience with rotundifolia.
Mine only turns red when it is within approx. 1.5 inches of the water's surface, total depth of water approx. 15inches allowing for substrate, they continue to turn a brighter red if left to grown...
I'm sure the first plant is NOT M.pteropus, the leaves appear too wide and there is no evidence of black spots to the undersides. Also, it appears there are thre parts to the main leaf in the photo, and this doesn't occur on any Java Fern I've seen :?