I’m still not sure what each piece is, but maybe it doesn’t matter. Can you make two patches, one for the inside and one for the outside? They could be sealed each other in the middle and to the pieces in the picture around the edges wherever TPU contacts TPU. In the spots where there is no TPU on either side you could sew it together and then use Aquaseal (that is the conventional way of fixing packrafts and it works fine).