Hello Tom,
thanks for the clarification. The sentence felt a little bumpy to me,
but I am native German speaker, so maybe it is just me then.
Since "they" means the tools, would changing
... the files they are used to build are included in the tarball.
to
... the files they use to build [it] are included in the tarball.
convey the intended meaning more clearly?
If not, that is fine and I am out of your hair :)
Thanks for your time!
Cheers
Martin Mai