HI Danny,
Now DRAM looks good. I believe Parity, Ten and ACT_n pins are not there in DDR3L. Those are for DDR4.
Is there anything else that could be a big problem besides the data line?
Ans: Data Mask, Data strobe has to be matched with Data lines. Earlier schematic it was not matching.
I think the wiring of DDR4 and DDR3L is similar, so I can do artwork by referring to the DDR4 schematic and PCB file.
Ans: Yes.
Mrudang