That's a dreadful wreck, lucky the outcome wasn't worse.
What's the cost for a left-foot throttle conversion? Will that need to be included in the 15K for the car?
From a quick squizz on carsales it appears 15K will just about get you into another 2013/14 LX or Zetec TDCi wagon, albeit one with more lifetime KM than your previous Mondy.
If you have to, the out-of-pocket cost to fix the faulty Powershift sensor issue (gearbox teardown, part replacement and reassembly) is around $2.5K - $3K. So not nice, but not the end of the world. If you buy from a dealer you'll get 3mo statutory warranty, and you can also buy a third-party mechanical warranty from the likes of NRMA/RACQ etc. Either should cover you if the issue arises after purchase, but it's a short window. If you're concerned about the transmission, get an OBD scanner and Forscan and check for
TCM trouble codes so you can claim it during that warranty period.
Don't forget to replace the baby's car capsule. I think most major brands offer a free replacement in the event of an accident these days.