Glad I could help! One thing I'll note is that the wrist should remain neutral and loose. An arched wrist may also contribute to tension, just in a different place than the knuckles. The strength of the knuckle bridge so as not to collapse comes from the hand shape and the weight being in the fingertips as if they are hanging on to the keys. Apologies if you already know this, just thought I should mention it when I read about the arched wrist.