Sounds to me like you'll need to create corresponding bit fields to those columns that you don't want edited after they calculate them.

Example:

CalcField1 = 100
CalcFieldEdited = 1

Basically, use a bit (1/0 value) for those corresponding field. As soon as the form is submitted, check the values inputted and calculated, then SET the corresponding trigger field/column to 0, meaning cannot edit.

Then in the calculate form, you'll need to add conditions in your WHERE clause that you use to build the form.
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Buh Bye!

Cheers,
Me