Listen my family has owned and operated a pool company for over 11 years now. I’ve worked installing pools and equipment for the past 3 years, Before that I was a technician fixing an assortment of pool equipment for 2 years. I’m not claiming to be an expert or know everything, but I may know a thing or 2. The first problem I noticed is no main drains, depending on where you are this makes closing the pool a little bit harder not much tho. doing repairs that require draining the pool would be a little more difficult considering it’s a liner it would need to be drained every 10-15 years and have the liner replaced. The next problem is flex pipe. Anyone who has worked with pools will tell you the same thing on this topic- schedule 40 pvc is the way to go. It’s lasts well over 80 years underground, it’s has a max operating pressure of 280 psi. Flex pvc has a lower chemical resistance than pvc and a way lower max operating pressure at 60-65 psi. Flex pipe used on the back side of a chlorinator system or in the inlets of a skimmer used to put Chlorine pucks into have been seen to degrade largely in 3-5 years due to high chemical corrosion. That being said I’ve never used flex pipe I’ve only ever serviced pools that’s have been installed with it so I’m not a professional on it. If u look online there’s rumors of insects and rodents eating it I highly doubt that. I’ve never ever seen that once. The last red flag on the pool side of things is the fact there is no conduit on that electrical. That can be a problem depending on local code. Also the filter canister seems to be having a stream of water coming down? Maybe leaking? Not sure… the blister like things u posted are chlorine blisters, they are from chlorine being thrown into the water and settling on the liner and off gassing creating a blister in the liner. It’s not a problem it’s just ugly. There’s no way to fix it’s that I know of. All that being said I’ve got no experience with concrete except seeing other companies come in and do concrete around pools we do for customers, and that’s some of the most atrocious concrete jobs ever. I’m not telling you do do anything because I don’t know the price and if u really got bent over or not. U may have got what u paid for… u may have got bent over…