We just have to add to our package, the proper bitmap files related to what we want to customize. Nothing is done "magically" without any additional intervention
By default we only think to work on fuselage : wings, tails, cfm56 ... however this is not sufficient for customization, if it lacks our needs we have to add it
Though rather to ask here, at first a search in the files present in objects folder and display them, would have been a proper reaction and a proper initiative to develop your sense of this design Don't wait other searching for you ...
So, the missing file for you are those 3 which should be updated accordingly :
737cabin_galley.dds
737cabin_galley_LIT.dds
737cabin_galley_NML.png