No...it isn't solved. Because, if he is 2 years behind, Layla etc should be 20...and long left high school. Or, Layla etc are only 16....whichever way you twist it like that, it just doesn't work. Again, I'll explain for the deaf people...setting it in 'high school' and making them '18' just causes too many problems (because they shouild be leaving school in a couple of months...not going on a summer break) and Steam will never...never go for it becasue there is a distinct difference in the story where half of the LI's do actually go to college (never mind the Iris scenes which Steam would shit a brick over) and there is discussion with the MC and Emily over him 'going' to college in the future.... Nyx is using the US system of schooling here.
This works and is what is should have been done in the first place (or just leave MC, Layla's ages etc and have them just starting college), but as we all know, Nyx likes to (for some reason) really push the acceptability boundaries.