Thanks for tagging me here! Didn’t notice this topic earlier.
I will explain quickly why I opted for moped:electric and mofa:electric, as I did earlier to @mueschel personally: *
I opted for mofa:electric to better indicate that it is a further specification of mofas. I.e. an electric mofa is not allowed with mofa=no, unless mofa:electric=yes. And vice versa; on access=no but mofa=yes, electric mofas are allowed. I didn’t think of this myself by the way, as it was discussed on the Dutch forum last year: G13 en elektrische mofa's - Nederland (Netherlands) - OpenStreetMap Community Forum
* If the consensus is to use the underscore variant, I will of course switch.
However, given electric_bicycle, using electric_* seems more in line. Although, mofas and mopeds have always been motorised, just not with an electric motor… In other words, an electric bicycle is way more different from a ‘normal’ bicycle, than an electric moped from a moped with an ice.