your trying to set a narrative that channel partners update a commitment and then send a "onion_routing_packet"
what you are not realising is what i said a few posts back. with the colourful image cycle of 1-9 alice to eric

you do know that users along a route cant create a commitment until they have first received a LN payment. else how will they even know what they have to update the channel by.

also they dont update the commitment. at the LN payment 'update' they update the channel to their peer
this channel update is not the network wide gossip channel update that just shows a channel is created and funded with its chain has preference and min sat dust amount

this channel update is a private message between channel partners that update their own micropayment promise.
this micropayment promise is measured in msat and includes the destinations payment_hash as the 'output'

its not the channels commitment that uses the channel partners pubkeys. its a "micropayment" msat format using the payment_hash

once an payment succeeds then they update the commitment. because then and only then has B deserved been paid by A.
if there is a route fail. then the Ln micropayment promise just gets dropped

please take some time to read ALL the bolts. and try not to fear moving away from your adamant desire to only read bolt 2