The feature is not designed primary for coloring the tabs of the files of different languages, but of different file types of same language. For example, there is opened a C++ project with the source code file communication_process_data.cpp and its header file communication_process_data.h and several more *.cpp and *.h files. So there are two files with same file name opened on which just the file extension at the end differs. The coloring of the file tab according to the file extension is quite helpful in such use cases, especially on longer file names and many files opened. The ability to highlight the file Readme.txt completely different to other text files with file extension .txt is also sometimes really useful. The user has just to make sure to define the names of individual files and the file name/extension patterns in an order to get the file tabs of individual files matched first and therefore the color of their file tabs selected first. So Readme.txt must be associated with a color above the color to use for files matching a wildcard pattern like *.txt.

I agree that the suggestion for an enhancement with an additional option like Apply patterns on fully qualified file name or Apply patterns on entire file name (with path) to force the wildcard patterns to apply not just on the name of a file, but on its fully qualified file name would make sense in the use case as described by you with different projects having files of same name as it is often the case for HTML projects with index.htm, robots.txt, .htaccess, menu.css, etc.

So in my opinion it would be a good idea to request such an enhancement by email to UltraEdit support or using the technical support form.