Will the changes on the template Performance Form appear on the already launched forms? Basically, will the existing Performance form be updated?
Is there a set up for this sync?
The only changes that can be reflected on a live PM form which you can change from (Form Template settings) page most of settings here will reflect on the live from, other than this (like changing in thing in the XML or using manage tempales) will not reflect to the live forms.
Please refer below SAP Note. Hope it's clarifies your query.
2077413 - PM Template Settings & Changes to Live Forms - Performance Management