Please example your problem in detail. Why did you manually changed the reverse proxy ? And what are you trying to achieve when there is good documentation on making the erpnext site SSL with lets encrypt.
How did you try to do this?
Why like this ? When there is multi-tenant setup already present.
Why manually? Any specific requirement ?
From all this I think as you have started the whole SSL process manually you might have to add SSl manually to the nginx for the site and also make it force redirect to HTTPS.