Often, your school won’t know unless you tell them. This is especially true of WL activity after the decision date. Your hs will know where they need to send your transcripts, so they will be sure of one acceptance.
At some schools, the CC may be involved at a level where the uni will notify them of the decision, sometimes before the student! This is far more common at private schools where the CC may want to be prepared for a parent who has been a big donor to his college to come storming in when junior was turned down in spite of those ties.
And at some schools - ours was like this - it was seen as paying it forward to make sure your CC had accurate information on decisions. Applicants benefit enormously from good data when they are deciding where to apply, and the CCs do a better job when they have this info.
At some schools, students populate their own naviancedecisions. At others, the ccs do it to ensure it is done and accurate.
This is a long answer for "it depends ".