Could you tell me something more about the innovations introduced by Stanwood?

I am not prepared on this research front. I confess to being more intuitive regarding mechanical dynamics, while still respecting the fundamental principles of Physics. Therefore, I would not want to claim to delve into a scientific treatise on the "leverage" of the key and its dynamics. The choices of the manufacturer must nonetheless be respected as much as possible, while experimenting to see if anything can be improved. On some instruments this is possible, by analyzing the dynamics of "that" instrument and deriving a possibility to improve its performance.

I was reading that his "method" is to create consistency in the weights starting from the hammers (which must decrease in weight linearly) and only afterwards move on to the lead weights. So, first weigh the hammers by shaping them or putting small weights in the wooden shank (which seems strange to me, but I don't know) and then weigh the keyboard. He criticizes wanting to compensate with lead weights in the key for inconsistencies in hammer weighing (perhaps one that weighs more or less than its two neighbors). If I understood correctly (but it's not certain), conceptually it is very similar to what you did with my piano, providing a linearity of hammer weight by choosing a light set and shaping them "ad hoc" to obtain a harmonious and linear decreasing weight from the bass hammers to the treble; subsequently, you moved on to the linearity of the lead weights and only at the end did you "refine" (correct my terminology) everything by utilizing the return springs to the capstan. I think it is more or less the same thing. The fact that Stanwood uses small lead weights in the hammers leaves me perplexed.