This is incorrect. The front-end for Fenix uses the Fenix and Android-components GitHub repos.
mozilla-central only contains GeckoView (the embedding API for Android) which uses Java for the API itself and Kotlin for all the unit tests.
mozilla-central only contains GeckoView (the embedding API for Android) which uses Java for the API itself and Kotlin for all the unit tests.
Being in a different repository, it didn't show up in OP's stats, either.