When adjusting the trimmers, make sure they're balanced to minimize DC offset between outputs, recommend having another DMM for that.
To measure the current, you need to measure the voltage between the 100R resistors and divide the voltage by 100. The total current for one side is the sum of all 4 of them.
There's an updated board on google drive that has a 10k trimmer with dn2540 that you can adjust the current till it's stable.
https://drive.google.com/file/d/16cuirLgLsadI1xa9c6OoaIqW6KevyZPa/view?usp=drive_link
Do you mean the Mini Shangri-La? The Shangri-La Jr is $4000 while the Mini is $1100.
I've tried the Jr but it sounded similar to the Mini so I didn't it was worth spending $4000 over it. Then I saw the ES-2a but with half the price and better build quality.