...so Maat is now representing the male?
I think the important point is that it's just a part of Ankh-f-n-Khonshu's father's name. In fact according to the Gardiner-Gunn translation his name is MNBSNMT. A footnote to this says that it is the father's name and that the method of spelling shows he was a foreigner. There is no clue to the vocalization.
For what it's worth you might like to know that the mother was a sistrum bearer of Amon Ra.
Personally I don't think the meaning of the names is all that important. For me they are convenient place-holders for the manifest mother/feminine and father/masculine forces. With Ankh-af-na-Khonsu they form a more earthy and manifest trinity to mirror the spiritual trinity of Nuit, Hadit, and Ra-Hoor-Khuit.
And what does it actually mean to "beat my breast" and "weave my spell"?
It's more of Crowley's poetic license with the stele translation. But the breast beating sounds passionate and self assertive in an active way that conforms with the masculine father principle. A spell on the other hand is a binding or a constraint. It pulls things together and suggests the feminine mother principle. That's just my opinion, take it or leave it.
I'm contemplating going along with the drop-replace and changing those names with something more close to heart
I know people who do that in their private practice. They even ditch Ankh-af-na-Khonsu and replace it with their own magical motto or the name, Baphomet.
Playing devils advocate here. It's worth bearing in mind that the paraphrase of the Stele is not part of the original manuscript of Liber Legis.
Some people claim that this means "change not so much as the style of a letter" does not apply to the adoration.
Personally I'm the kind of guy who's happy to let names stand as they are.