Having a look at this on a proper monitor I can't see where the traces go as there's a sticker and cable in the way, as well as the traces hiding under the chip itself.
I found
this thread discussing the same chip and a couple have 8 pins used in the connector, following links to deskthority revealed more but none quite the same as yours. To quote from
here:
PTPM754DR Pinout like in the datasheet of the old IC TPM754, you have to omit the pins 15, 16, 17 and 18 of the PTPM754DR (they are connected to GND), the other pins are the same as on both IC versions
So if you have a multimeter you could test continuity from the pins on that chip using the schematic on page 3 to work out what goes where.
If that's like an alien language to you perhaps it would be easier if you said which keyboard or laptop you found this trackpad in, it might help with searching for someone who's already done the work.
Or you could take off the sticker and post another pic (and one with the ribbon bent up out of the way?) and I'll have another go at tracing it out digitally - if possible a clearer pic of the side with the chips would be great too, I'm not sure some if I'm seeing vias (holes which link to the other side) or not in a couple of places. Looks like you're in Australia so pics taken in direct sunlight should come out nicely