Standard lithium ion charging is CC/CV with C/10 termination. So for a 10s 5ah pack, that means constant current until you hit 42v, then taper off the current until you get to 0.5a, then stop. At this point you are100% full.
With diebiems, there are some other factors. To get full charge, you need a +0.6v offset for the diode. For the automatic behavior you need another +3v. If you add this +3v, in theory if I understand correctly, the bms still cut charge at 42v (if cells all charged equally) while the charger is set up for 45.6v. This means you never get to the CV portion of the charge, and will never get to 100% full (Which is probably better for your cells in the long run).
10s is 42v, diebems offset (+0.6v, +3v): 45.6v
12s is 50.4v, offset: 54v
Neither 48A nor 54A cover that range.
One way you could go is, If you get the 54A and a DPS/DPH psu, you can get what you need from one PSU. The DPS/DPH are limited to 51v I think… So you can set up the meanwell for 54v, and for 12s plug straight into the meanwell, for 12s go through the DPS/DPH unit to drop it down to 45.6.
In a way this is similar to figuring out how to charge 10s, 12s and 13s. without diebiems.
BTW I really like putting something like this inline on the output
https://www.aliexpress.com/item/ATORCH-Accurate-Energy-Meter-Voltage-Current-Power-300-100A-AC-Voltmeter-Ammeter-Greem-Backlight-Overload-Alarm/32821731871.html
measures watt-hours transferred, among other things. The numbers are precise but not necessarily accurate. This particular version is single piece (no separate shunt box), and LARGE. 0-300v, 0-100a.