Yes, that's right. The following changes need to be made:
1. The `fail-callback` parameter to `p4-form-callback` should be renamed `failure-callback` to match the new variable.
2. The `fail-callback` keyword argument to `p4-form-command` should be renamed `failure-callback` to match the new variable.
3. There should be a new `success-callback` argument to `p4-form-callback` which should be used to initialize the `p4-form-commit-success-callback` variable in the buffer.
4. There should be a new `success-callback` keyword argument to `p4-form-command` which should be passed to `p4-form-callback` via a lexically bound variable in the `lexical-let*`.
5. There should be a line of documentation for `p4-form-command` explaining what the new keyword argument does.