I don't want to seem arrogant, but are you alive there? If yes, please accept the last pull request)
In addition to the “Improvements”, I think that hydrolox engiens are not needed, or we also need to do kerolox, metolox ect, and this will add confusion to the existing methods.
It seems to me that sorting by: ORCS, FRCS is enough and it is worth developing the topic of sorting by engine design, and not by fuel.