About EF-S mount, here we can see that there is a gap between the lens mount and NFE mount. The EF-S lens bottom has touched the internal structure of NFE before the bayonet getting together.
Please note the grey bottom of the lens in the second image. This is the mechanical limit to prevent using EF-S lens on EF mount. On the other side, you could use EF lens on EF-S mount.
Since the shutter module of SL42 is also very close to the mount, EF-S is not available for both NFE and SL42.
If you would like to try extra thin adapter to get rid of the mechanical limit, it might work but the EF-S lens will not focus to infinity.