Problem with missing dependency in build script

Hello forum,

we are currently experiencing an error and wanted to ask you about any hints…

A little bit of background:

- We have a build script in our project that generates a stand-alone IDE. It worked previously perfect.
- Now, we just merged two languages (LanguageA and LanguageB) and removed one of them (Language B).
- We removed all dependencies that we saw.  Every language and the solutions based on these languages are building and working fine.
- When we execute the script to build a stand-alone IDE however, we experience the following error:

cannot find used language in dependencies: LanguageB
-- -- was input node: [modules] BuildMps_Language "LanguageC"[860303340950024189] in buildScripts.build.The error appears on two computers and invalidating caches did not solve the issue.

We looked all over the place (even in the file system), but could not find any dependency. Do you have any ideas, where we can look?
E.g. what is the effect of the Command+R action (importing a concept): where do we find these dependencies?

Any ideas are more than welcome,

Christian