From the documentation:
noteStalled (delay: u32, best_finalized_block_number: u32) interface: api.tx.grandpa.noteStalled summary: Note that the current authority set of the GRANDPA finality gadget has stalled. This will trigger a forced authority set change at the beginning of the next session, to be enacted delay blocks after that. The delay should be high enough to safely assume that the block signalling the forced change will not be re-orged (e.g. 1000 blocks). The GRANDPA voters will start the new authority set using the given finalized block as base. Only callable by root.
But what does it mean should I give the last generated block as the best finalized block or the one already finalized or the one I would like to continue from? In this case 57281 or 57354?
I tried to use the block 57281 and 100 as delay, nothing happened at block 57382