I was just reading adding heatsinks to the top of the fets almost does nothing. According to Rew:
"Yes. Note that cooling the “top” of the fets (the side you can see without desoldering) is useless. I’ve found a datasheet that mentions 10x the thermal resistance to that side of the case than to the side that you’re planning on cooling. Note that the high-side-FET drains are all connected to “VMOT”. So you can easily solder all three of them to a big copper plate (connect to VMOT as well!) and a heatsink.
On the other side, the three drains are connected to the motor phases. So you’d need an L-shaped copper conductor and then an insulated heatsink on that. Consider: There is also the IRFP7530. The problem is that it is a lot bigger: TO247."
Also the temp sensors aren’t really on the fets just nearby and there’s really only one sensor for all the fets for now