If I've understood your post right, then you are correct in that the K-factor will be reduced for the games that count towards the rating list.
This
rating regulation may be important:
7.1.3 The closing date for tournaments for a list is 3 days before the date of the list; tournaments ending before or on that day may be rated on the list. Official FIDE events may be rated on the list even if they end on the last day before the list date.
So if the April tournament ended on/after the 29th April (or maybe the 28th, depending on how FIDE count as "three days before the list"), then it is absolutely correct that it is rated on the June list (and this is not the fault of any organiser). If it ended before then, it depends on when the IRO for that country sent the tournament to FIDE (so it may not even be the fault of the tournament organiser, but rather someone from the federation). Same goes for the May tournament (so it would need to be sent by the 28th or 29th for it to count, if it ends on the 30th/31st it definitely won't count but if it ends on the 28th/29th then it may not be sent in time). And if the event ends in June (e.g. it's 4 rounds in May and 5 rounds in June), all rounds will count towards the July list.
Wadih Khoury wrote: ↑Sun May 21, 2023 7:32 pm
Wouldn't it be fairer and more logical to check which month the tournament relates to?
That can cause more/different problems - if someone on K=40 plays 17 games that count towards one list (so the K remains unchanged), and then there is a late reported result that adds 9 more games (that would change the K to 26), do you go back to the old list and recalculate it? This will have knock on effects on players seeking titles (whether it be the player that is affected, or any of their opponents in future tournaments looking to hit a rating target or get a norm).
Wadih Khoury wrote: ↑Sun May 21, 2023 7:32 pm
...yet it looks like he will be punished for the organisers' delays! (he could lose up to 30 points if my understanding of the above is correct, ignoring his next 4 games' outcome)
It's worth bearing in mind that if he had underperformed (and was due to lose rating), he would be benefitting from any delays, not losing out. And if he's underrated, then he will gain more/lose fewer points going forward as his expected score will be lower, so it will self correct eventually.