TLDR: HP nerfs makes the item's stats too weak since it's not cost effective and outclassed by other items. CD nerf is justified and is fine, makes the item have more counterplay and time to pressure-
Hi, I'm a now diamond II tank player and here are my thoughts on the Righteous glory nerfs. The current PBE nerfs to Righteous Glory will make the item unviable and will make it never be built ever again in pro play. In it's original release stages, it had 500 hp and 60 sec CD and nobody built it. Making it 500 hp with a 90 sec CD will make it even worse. The reason why nobody built is the fact the tank stats are not worth the cost. For the same cost, you could get a randuins to get the same amount of health while also getting a lot of armor, AS slows and a AoE slow. Righteous glory only gives you a little bit of mana and regen, which is not worth. While the active is very strong and a bit overpowered at 60 seconds CD, making it 500 hp will make the item unviable since it will not offer good enough stats to be worth it's cost. People will go back to buying randuins instead of it just for that reason. At 600 hp, the 100 hp makes it a viable option since it has competitive stats with randuins while also having utility and has good enough utility to be just as strong as warmogs which has better stats with 800 hp and better regen. At 500 hp, it doesn't have any of that and is just outclassed by the fact its stats are just too weak.
While the stats changes will make the item unviable, the CD of the active won't. I agree with making it 90 secs because it has no risk in using it to try to engage and you can't get punished when it's on CD since the CD is too short. Increasing it to 90 secs makes it have more counterplay in the way you can put pressure for a longer period of time if they mess up their engage and you properly dissengage. That change is fine and should be put to live, but the HP one shouldn't.
If this change comes to live, it will greatly nerf a lot of balanced champions who have been viable due the power of this item to offer engage power with decent stats like Maokai and Nautilus. Nerfing the CD only makes the item require take more skill and have more counterplay which is good and healthy, making it have bad stats makes it unviable.