They are acrow props for use during construction. Are they seriously concreted into the ground? Your inspector is a halfwit. This is how you would prop a floor during repair. I’d get a builder in to have a look
a few other issues, no ant capping, the packer on the stump is too big and the bearer looks crippled mid span, ie not over a stump.
It is very unusual to concrete under the house unless it is to make it usable. In this case they might be hiding something, the fans make me suspicious about a damp subfloor
Building Inspectors carry professional indemnity insurance, at least the reputable ones do.
If I found my sub floor/foundations consisted of acrow props and the building inspector missed it, I would be engaging with a lawyer to send a letter of demand to the building inspector to pay for the rectification of the structural issues that he/she was paid to discover.
You engaged with a building inspector to provide advice for a fee. If his/her advice causes you to suffer a financial loss then the professional indemnity insurance should cover your loss.
Suggest you check the moisture levels in the subfloor, house, and cupboards. Sloping block, concreted subfloor, poor constuction, strange repairs, and forced ventilation indicate this might be a concern. Also check for evidence of past mould infestations in cupboards and other out of the way places that may not have been recently painted for sale. Warm dry weather can mask such issues that become evident as soon as moisture and humidity increases whilst temperature decreases in autumn and winter. Your inspector should have noted any areas of concern here.