I won't pretend to be an expert, just highlighting the discrepancies as I think you're comparing apples to oranges.
Your question seems to have been based on Muscle Mass accuracy. Of course I'm sure we'd all agree home scales will not be "accurate" at calculating this.
PP asked if 37.5% Muscle Rate was "realistic" and it said yes as 25 to 33 was typical. I believe you stated 30 was the max, yet it's merely in the middle of this "typical range". But is your 30 max Rate or Mass, as they seem to be measured differently?
My scales show my Muscle Mass as a weight, suspiciously similar to my Fat-Free Mass.
Skeletal Muscle is 41%, which is the low end of average for my stats. I'm not muscular or athletic enough at all, so I don't think it is based on the Muscle Rate percentage. 40-50% is my quoted average for this measurement on the scales.
I just use it as a guide on my progress and celebrated when my readings turned from a starting point of mostly red/ orange to all green, for healthy/ average. (BMI 38 to 20.)
I hope OP finds better success with MJ.