Project Role restriction for business users - at Legal Entity Level?

Business are maintaining hierarchy as Business unit and under BU legal entities. They have 1 BU and 2 Legal entities.

Users want to restrict the project information based on legal entity instead of business unit.

Normally using the seeded role like Project Accountant and Project Manager with the Business unit Data access for Limiting the access on the UI

but since this BU was repurposed from a different one, the people are able to see the Historical data of the previous BU and that is not what business wants.

This is compliance issue, need help with a Custom Security Role.

Tried, to create a Custom role, whether is is possible to restrict via Legal Entity.