I guess I would evaluate the cloudron webmailer without migrating sieve scripts created by SOGo first. Since sieve scripts run anyways on the server and not in the mail client, they don't depend on SOGo being actively used (or even still installed) for the server-side filtering to apply.
Unless of course one wants to evaluate the sieve filter creation and management capability of the mail client specifically, at which point one can test this with new filters and to not disrupt filters used in production, simply do not touch them.