It feels like the author just think the concept of synesthesia as cool and decided to make this without researching further. Not to mention it's another boys meet girl story.
@Shioneri I agree totally with you, the guy's definition of synesthesia is lacking a lot. Plus, the girl's 'discoloration disease'? Wtf, the only 'discoloration' in humans and other living creatures is the physical discoloration, for example vitiligo or albinism. 'Color deficiency' would have been better, or even more specific 'color blindness'. I really like the art, but the authors need to do their research properly.
@miraianna the author may mean something and the translations mean something else in English. like in Spanish, most of the words have a masculine and/or feminine part to it while English words doesn't have those changes.
basically you can say there is no 'true' translation between languages because different languages are not just switching the symbols and grammar. they were made differently and they are probably not based on each other.
@Satriox No. The work does not need the sci-fi tag. It uses the synesthesia concept as a mere platform, but does not explore/build upon the science itself in depth.