Alliance vs. Engines endgame analysis (move 47)

The engine chose 46...a2, as expected.  Here's the situation, including the latest move by both parties:

Previously I had offered analysis that remains relevant in the current position:

"46.Re1 a2 47.Kc2 Rf3 48.Rxe4+ Ka3 49.Re1 Rxf2+ 50.Kc3 Rg2
seems like a reasonable continuation to me, and when we get there (if we do), we can re-evaluate the situation and whether there are remaining chances to play for.  My guess is that after 51.Rf1 Rxg4, black's anticipated maneuver Rg4-Rb4-Rb1 and promoting won't be stoppable then, so that will put an end to the game."

Other thoughts and/or improvements for us?

Black can probably choose 50. ... Rb2 and win in another way. My intuition was that we were lost once black played Kb4, and on this occasion I suspect it was right.

it seems there are no alternative to 47.Kc2; let's then  "drink the cup of bitterness and gall to its darkest dregs"