, since I have grown the lemoinei for only a year, I don't really know whether this variety is more temperamental than the bifurcatum. I have grown bifurcatum for 30 or more years and know that this variety is very undemanding. I do know that you have to be very careful when growing any of the staghorns in pots. Since they are not terrestrial plants, but are being grown as a terrestrial, they are not able to dry out very quickly and are getting a lot of nutrients that they may have trouble assimilating. If you must grow it in a pot, I would suggest that you at least open up the potting media with coarse perlite. I would use an equal volume of perlite as is the volume of potting soil.
Why don't you get another staghorn, but this time a bifurcatum (look for the Netherlands sub-variety) so that you can grow the two side-by-side? You'll then see which does better for you.
Speaking of mounting, you can virtually hang a mounted staghorn anywhere there is warmth and bright light. Depending on the mount, you can also sit the mounted plant on a counter, shelf, plant stand, etc., just like you do a potted plant. This is called growing them on a "raft". Natural cork makes a great mount and it can be either hung or used as a raft. Many other woods can be used equally well.
Like you, I am stumped why your plant's fronds look the way they do. I am sorry I couldn't be of more help.