I appreciate your post, as it looks like you have put some effort into it.
My premise still stands that the "Transfer Net Spend" as Sky like to present it to an average punter is a meaningless figure to football clubs.
Clubs don't look at, or use this figure in their plans and calculations. We shouldn't be using it either if we want to accurately describe our situation.
What clubs are interested in is:
1. Total cost of ownership of the player (wages plus amortisation)
2. Actual cash flow behind the transfers (which can be very different to the Sky touted "net spend")
It's too simplistic to quote the "net spend" like the original poster did and complain that we have negative value.
Regarding the figures you're quoting, I mostly agree with them. Looking from the outside, yes we could spend more money this summer. But the management and coaching staff decided it's not necessary/beneficial in the long-term (or maybe simply the players they really wanted were not available). I have trust in their decisions as they are much better informed then us to make them.