Kansas Ref wroteI don't think I have ever seen an NF-level ref change their block/charge call once it's been made.
With a few exceptions where my partner comes in to tell me that he had a travel before my foul, or a held ball before my foul, I have never, ever, in thirty-eight years, changed a high school foul call of any type (also exception for wrong number).
(We'll once, when I had "White" player "fouling" another "White" player. Not my best call of the night.)