The fact that your PO did not find you in violation would indeed be arguable in court as evidence no real violation occurred. Why the PO's supervisor told the PO to violate you, months after the fact, is likely to be a subject of inquiry.
The foregoing is for general information purposes and does not establish an attorney-client relationship.
If you are cited for a probation violation, you would still be entitled to a hearing before the Judge who would ultimately make the determination as to whether you were in violation of the terms of your probation. The opinion of the officer may be a factor in determining whether you violated your probation and as to what puinishment should be imposed. You should consult wiith an attorney to determine the exact practice employed in your area, and to be prepared if action is taken against you.