Comparing the TLC5967 DBQ package and the TLC59248 DBQ, it appears the TLC59248 THja was derived with a 1 sided board.
TLC5927: 99.8 C/W single layer JEDEC standard.
TLC59248: 91.5 C/W is very close to the 99.8 above.
Using the same scaling factor for 4 layer 2S2P you get ~56C/W for the TLC59248 in a 2S2P board.
Here are the general specifications for the JEDEC thermal resistance standards, called JESD documents.