Quote from @fathafluff in topic Note Color Question
Thanks to the replies of @Rick G. and @hmmueller, we know there are workarounds: markers for slurs and triplets, user object beam.hmm for the beams (with the appropriate color set).
With this tool, the necessary markers and beam objects are cretaed. It contains an algorithm to determine the position and final stemlength of the beam object and the position af the triplet marker, but maybe you need to change them for an optimal result.
Installation: After downloading this tool, start NWC, open any file and drag and drop the tool onto the NWC window and confirm.
Use: Select a group of notes ( only the first note needs to be colored), and press ALt-F8 to run the tool.