I may have found an alternative. Pseudogrey is mentioned but no signs of it in the application. Delalaboratory
https://code.google.com/archive/p/delaboratory/downloads
Obviously I shouldn’t have stuck curves on the top of the layer stack but wanted to see if it functioned as the others. The controls if any for all of the layers that are added remain active. Very photographer friendly. Just wish it had gimp levels as being able to set the output span can be very useful.
I had to edit the make file to get it to compile on Linux 64bit by forcing the selection. Just commented out the if else around it.
Quick play
It couldn’t open a user directory and I didn’t check if it can save a file. Hope so
John