Sounds like his data set goes back almost 30 years. Not too sure how many KHL goalies would be in there. The draft age doesn't really matter. It compares D+1, D+2, etc. years.
I'm not super familiar with the model. It's definitely a lot more complicated than how I tried to paraphrase it. It's basically
NHLe with his own tweaks if you're familiar with that.
Either way I feel like it wouldn't work too well for Russian goalies. It might be a model that works really well for players from Sweden, Finland, CHL etc but I think there are too many variables to consider for it to work well in this specific case.
Also if it doesn't take into account draft age then that's one variable missing already since Konovalov was a triple overager when he was selected. And obviously size is something that matters for goalies too.
But most importantly looking at save percentages for goalies in KHL really doesn't tell you much because it's such a low-scoring league and where even average goaltenders has insane numbers. It appears to me that a goalie's numbers in KHL is more down to the system the team plays and how good its defensive players are, and then the goalie's numbers is a byproduct of that.
For instance, Konovalov's .930 svs% in 18/19 may look good but wasn't that special. His backup Alexander Salak had slightly better GAA and slightly worse SV% at .922, but had slightly better numbers in the playoffs both in GAA and SV%. The third-string goalie on that team had 1.30 GAA and .953 svs%, albeit in only five games but all of this together paints a pretty clear picture that Konovalov's numbers that year wasn't really about him but about the team.
This past season Konovalov lost the starting job to NHL flame-out Eddie Pasquale, but again both of them had near identical numbers, Pasquale a .925 and Konovalov .923. Season before that Konovalov had .912 in 40 games while his backup had .927 in 25 games.
So yeah...there's nothing in his numbers that, to me, suggests that he is anything special. That, in combination with his size, makes me highly dubious about how good of a prospect he is, but I haven't seen much footage on him so I guess it is possible that he looks great in the eye test and is a legit NHL prospect, but I'm not holding my breath.