Correct, the build system is written in Python, with the definitions of rules for each module in files such as https://searchfox.org/mozilla-central/source/tool

Correct, the build system is written in Python, with the definitions of rules for each module in files such as https://searchfox.org/mozilla-central/source/toolkit/library/moz.build https://searchfox.org/mozilla-central/source/toolkit/library...