The old Eyeon era Lua scriptlib functions still work in Fusion 8/9 based Lua scripts. You don't actually have to aggressively go in and rename the functions to all to use the bmd.* prefix.
It was elements in a Lua script that relied on "pairs", lua-fs & readdir, or the IUP window manager that on longer work and caused a majority of compatibility issues.
Also adding Linux/Mac support to a previous Windows only Lua script is typically a matter of simply handling the folder slash direction.
When possible I try to retain the widest range of support for Fusion versions.