If "somebody" either:
a. made a [custom filetype](https://www.geany.org/manual/current/index.html#custom-filetypes) which needs an existing lexer which is "good enough" but anybody who wants it can do it, or
b. created a new lexer and had it accepted at https://github.com/ScintillaOrg/lexilla and then made a PR to add it as part of a built-in filetype (C and C++ and Geany internals skills needed).