For indexing problems in general read here . But the rogue of nexus was last updated over 40 days ago. And none of the other games are indexed either. A game can get delisted temporarily after an update and waiting times can be over 40 days to get redindexed. But with several games I suspect other reasons. There is also no link on the publisher's homepage to Itch and they claim to be the developer on their homepage.
If you have split ways with the publisher you should look into the legal situaion if you still own your own game and how things are for publishing. While being a different magnitude, the developers of Pathfinder Kingmaker found out the hard way that they do not own their own game.
The Itch version appears #2 on internet search, so I assume it was indexed once or there are enough links to the games for search to find it. #4 is the youtube release video with 70 views.
A web version would not work on Steam of course. But it could be uploaded to other platforms or your own homepage. And you will see games that have in their settings check boxes for sending anonymous data. Also, I imagine you could collect certain data points about how the game is played without worrying about personal data protection laws. That's not gonna work for things where you connect the data to people.
Those kpi things you mentioned are for subscription based games. Especially the churn rate. You do not have a churn rate. Of course you could try to estimate how good your game is, by how long people play it. But you would need a lot of players to begin with to try extract why people like the game.
So my opinion about applying kpi for a game like rogue of nexus can be summarized by this short reddit from 2 years ago https://www.reddit.com/r/gamedev/comments/13y8tcy/what_would_be_potential_kpis_f...
I believe finding honest play testers for development and marketing the game to the target audience to be more helpful than looking for obscure data points that will only be usefull if you already have enough players to have statistics. It is the also the idea behind https://itch.io/board/255031/get-feedback , but there is not that many readers there. Finding unpaid honest testers is hard, so I understand the desire to replace that with data analysis.
The thing with the early death confuses me. I happen to play a roguelike here and there. It is part of the game mechanic. People of the target audience would not be deterred by the very game mechanic they liked and which made them try the game. They like difficulty. If there is a miscommunication and players think this to be a regular rpg and then they are confronted with the roguelike style restart, that's a recipe for disliking the game. Regular rpg do have bad ends and game over screens too, so it is not that obvious that dying here and there is the way the game is meant to be played.