Does a lateral promotion show up on my ERB?

For lateral appointment to CPL, the date the lateral appointment action was initiated will be shown. Documents for such appointment include, but are not limited to, DA-4187, the AAA–117 (Enlisted Advancement Report) for Soldiers qualified for promotion and the first-line leader’s monthly counseling record.
A Soldier that is in a non/promotable status and will not be selected, promoted, advanced, appointed to a higher rank, or laterally appointed to CPL.
eMILPO - Users will not update their own records or Soldier records outside their current lines of authority regardless of permissions. Use of eMILPO and eMILPO Enterprise Datastore is a revocable privilege, subject to monitoring and performance testing

Your SRB will show that you hold the rank of CPL in the middle top of the sheet. Outside of that, you can be slotted in a 20 level slot in your assignment history. Those are really the only two ways to identify a CPL on an SRB as your rank history has SPC/CPL combined since it’s the same grade it won’t change your DOR.