well I wouldn’t make big changes for two reasons:
1:The plan has been working
2:The athlete needs to qualify first before worrying about Worlds.
Get in the meets before the trials as I suggested.
With the weights, you should be able to go with 3s lower body for some time and still have the capacity to drop the numbers but I’d stay at 95% and above. Remember, the same weight/rep scheme will actually get easier due to familiarity, allowing comp to coincide, before the plateau begins to cause strength losses. At that point you can reduce reps/poundage.
Your last point about the difference in race numbers between 100s and 200s is prob valid up to a point though I wouldn’t go below 4 for the 100 even with S-to-L.
With L-to-S, you might get away with 3 rather than 4 200s due to the SE background difference but with the possibility of doubling in meets, it would be unlikely to find enough of one event but not the other.