Part of source files in org.eclipse.wst.sse.core should be regenerated from JFlex grammar files in directory DevTimeSupport, but they require JFlex 1.2.2 for correct transformation (Debian has newer version). Migration to newer JFlex seems not going to happen very soon in upstream[1]

There are still some binary resource files in org.eclipse.wst.jsdt.core (part1.rsc, start1.rsc etc.), but I could not trace their origin and if and how they can be regenerated. Seems the same files are present in jdt parser and also other eclipse plugins. Should be regenerated when possible.

[1] https://bugs.eclipse.org/bugs/show_bug.cgi?id=296976

