"While the grammar is mostly regular here, two things make this challenging: the nonsensical assignment of genders to nouns and (...)"
The given examples for weird assignment of genders are inadequate because they are explained by common rules.
Das Mädchen: Diminutive words are always neutral, and Mädchen is the diminutive of Magd.
Die Männlichkeit: Words ending on 'keit', 'heit', or 'ung' are always female.
"..., but imagine trying to hear the difference between Rat and Rad over a bad phone line."
It does not make a difference if the phone line is good or bad; the words Rat and Rad are pronounced identical, thanks to the Auslautverhärtung.