FWIW Medium limbs rated 35# or reg riser run 45-55 ish on my shorter 19" Pinnacle 2 riser.
Have not put my 35# limbs on a 23 or 25" riser so dunno how close to spec they are.
I wanted a 50# at 28" and called Tradtech/Lancaster and that's what they sent me, it hit my spec on the money, with the limbs about half way cranked.
Scale showed 2# per rev, peaked at 58 but felt a bit funky. Smooth to low 50's, a bit of a dog at 46#, 50 seems to be right in the groove feel and perf wise.
My limbs are Blackmax and they are NOT rated for a shorter riser.
Tradtech took my info and got me what I needed.
The formula to figure it out comes close, but there are a lot of variables. With a Tradtech purchase they hit your spec +/- 1 lb.