Has anyone ever come across an overflow drain system for a water heater like the ones in the photos? I don’t see anything wrong with it because most of the homes I’ve seen so far don’t go this far, but would like to hear some other views on this.
Are they using the line as an indirect waste receptor for the TPRV? The discharge point should be outside the building and I presume it’s going in the crawl, which is a no no.
The answer to your two questions is yes they are using it as an indirect waste receptor for the TPRV and yes the discharge point is in the crawl space.
You should be able to see the end of the TPR opening.
How would you know if it is leaking and also dumping drains into dirt under the crawlspace is not proper.
Dumping water into the crawl would create an issue all on its own, but if the water heater is either leaking from one or both sources then you would have other issues to deal with.
As for a level of importance, what are the chances it will leak? I would mention it but it would not be of big importance. The worst that could happen is a wet crawlspace.