Alanfraserpiano
OK, let's keep our context clear here: remember, for as many different tonal colours we want as many different touches as possible.
1) Your "slack finger letting the key come part way up after hitting bottom" is a beautiful way of controlling the key for ultra-velvet and beautifully rounded, gentle tone. Playing to the bottom of the key is of course a crucial skill and central to our thesis, but the slack-finger variant is a highly evolved alternative that has many applications.
2) When playing to the bottom of the key, the question is HOW. There are many ways.
a) Your solution about "re-embedding" the finger reminds me of my book chapter, "Pressing & Holding in Legato," where I speak about a lesson I gave on Liszt . Please review this to see what I'm talking about.
b) It is also possible go all the way to the keybed but not , that I get into more in my second book.
c) Somewhere in between is the "Russian School" of rich, fleshy contact with the key - but a contact that cultivates suppleness through the whole hand and arm instead inhibiting flexibility.
There are others but I think I've made my point...
AFF
PS Gould's Steinway is in Ottawa but they dropped it and it apparently doesn't sound the same any more. I haven't had the chance to find out myself. His CHICKERING is in McMaster University's Music Department, and I actually saw it once there but did not have the chance to play it. Apparently it as well has not been maintained and so doesn't sound as it did when our Canadian Maestro played on it...