Everything done according to instructions, Lab data from CGATS exported as .txt into appropriate curves folder, then dropped over QTR-Linearize-Quad droplet together with .quad file. The droplet apparently does its job, however, I only see an “-out.txt” file in the curves folder and the original .quad, no modified “-lin.quad” shows up.
OK, answering my own question if everyone interested, problem solved:
Opening both files with the '“open” command within the droplet app is the only way I could get a -lin.quad
For the new curve to show up on the list one must restart PrintTool.