Desig considerations for a 10k va inverter
Can I just change the MOSFETs to CSD18536KTT and use higher power
  transformers to change the design to a 10kva one?


The original 800 VA TI design uses 4 x MOSFETs (in a H bridge) with absolute maximum ratings of 40 V and 100 A. Assuming that the 40 V rating was adequate for a 12 V battery, to get an output of 800 VA means a current of 67 A from the battery so, a rating of 100 A for the MOSFETs seems adequate.

The new MOSFETs you propose have ratings of 60 V and 200 A. Given that you could now power them from an 18 volt battery (because the voltage rating is larger) and, given that 200 A derates to 133 amps (using the same derating as the TI design), the output power from these devices is, on the face of it, limited to 18 V x 133 A = 2400 VA.

This likely means that you will need 4 or 5 times the number of transistors to achieve 10 kVA.

Yes, you'll certainly need higher power transformers.