Could you make the Exchange Rates to be changeable only if you have the correct permission on your user.
This has been implemented - details here: https://stayntouch.freshdesk.com/support/solutions/articles/24000051291-stayntouch-pms-release-notes-v5-20-19-february-2020#Access-to-Multi-Currency-Now-Permission-Driven
Could you make the Exchange Rates to be changeable only if you have the correct permission on your user.