It would be possible to make the adventure modules viewable in the ruleset simply by including 5E in the acceptfrom tag, however, that would not make any npc's or encounters usable. Trying to open a 5e npc record would throw an error.
However, if being able to otherwise read your module inside of the ruleset would be useful, and providing that It wouldn't somehow violate some inviolate rule here, that is possible.
You would have to rebuild the encounters with more appropriate npc's from C&C, AD&D or any other compatible OSR rules system, which likely you would want to do anyway. Once I can get the
C.O.O.L. Beasts project fully launched, there will be a large influx of new creatures available in a bestiary, so ultimately, that's not going to be an issue.
It should be noted however: Changing the acceptfrom tag would make any 5e asset viewable in your module list including things that you might not want to have viewable. It is an all or nothing thing. Since all of the official stuff is encrypted, you can't do it at the module side of things. It could only be done from the ruleset side, which means everything 5e you have would show up in the list. There also wouldn't be any way to distinguish it from any C&C or AD&D modules you might have.
Beware what you wish for.