djvj, seems you can already convert HS databases to AM ones, looking at their docs:
You can also import romlists from mame listxml files as well as gamelists for
other frontends. Supported source files include: *.lst (MameWah lists), *.txt
(Attract-Mode lists) and *.xml (Mame listxml, listsoftware and HyperSpin lists):
attract --import-romlist <source_file> [emulator name]