Legacy tv-4.0 vs TV Extensions 6.5

I’m trying to figure out if apps built/signed with TV Extensions 6.5 / Tizen Studio 4.5.1 should be backwards compatible with a TV produced with tv4.0. Is there ever a need to import older sdk components into Tizen Studio, and if so, where do I point the package manager? Right now, it’s defaulted to package repo: Index of /sdk/tizenstudio/
while Samsung Tizen TV SDK seems to be fixed at https://sdf.samsungcloudcdn.com/Public/smart_tv_sdk/releases/samsung_tizen_studio_tv_sdk/stv_ext_public/TV