Firstly, Halle is now a 500, but some of Fedr's Halle wins will register as 250s as they were won before it was converted. It's still Halle, the same place, and similar draws (and finals used to be Bo5 even when it was a 250). Now, we don't even have Bo5 finals in masters. As a result, that wipes out a good chunk of Fedr's 250s after Halle's conversion.
But it's not that simple. If any of Fedalovic wins more of the 250/500s, then afterwards, they may be too tired to win bigger titles, or it may wear on them mentally for the following titles (i.e. mid-season burnout). The physical/mental tolls are cumulative. The burnout of overplaying is real (see Djokr's 2011 fall season, or MuryGOAT's post-fall-2016 run). Yes, 250/500s 'can' be easy to win, but it's not a given. Matches still have to be played (see this year's Doha19, RBA d. Djokr). Dubai/Halle/Basel/Queens have always been tough, almost masters level, and some were won with more difficult draw-paths than some masters wins. Don't look down on them too much. How about that Eastborne title that kept Djokr from a title drought for about a year in 2017-2018? How come he didn't have other 500's if they were so easy to win? Even if he was slumping, but they were easy to win, so no need for a well-playing Djokr, right?
Fedr plays the 500s partly (or mainly) bc 4 are required every year for top players (he usually played Rotterdam, Dubai, Halle, Basel). It was his job to play 4. The fact that he won many of them can't be held against him if Djokodal won less, and as top players, they TOO are required to play 4x 500s per year. If they don't play them, then it's on them, and it's their loss on the stat sheet.
More importantly, Fedr's 250/500s are not titles to 'fill' gaps that are not even there. Fedr still leads the titles at slams, is very close in masters titles, and still leads in WTF titles over Djokr (Nadl has zero). Perhaps if Fedr was behind in slam titles, had half Djokodal's masters, and half their WTFs, THEN perhaps we can dismiss/downgrade Fedr's 250/500s wins. But that's not the case, and never was, and likely never will be, bc at this juncture, it's impossible for Djokodal to each double Fedr's slams/masters/WTF going forward.
So... Fedr's 250/500s are legacy enhancing.
I hope he wins more.