Nonsense. It only happens after prolonged massive intakes (A man who intentionally took 60mg/day for a year and 30mg for several years before that is one of the few examples found in literature.) and the signs are liver and kidney failure. It's completely unrealistic you could get that much from anything resembling normal food, vegan or otherwise.
Getting too much copper is virtually impossible unless you have a rare genetic disorder. The excess copper is excreted in bile. The defficiency on the other hand is widespread, it doesn't show in the blood tests and the symptoms are both vague and insidious. (Chiefly a constant lack of energy, brain fog and incurable anemia)
"the body can synthesize glucose" is a horribly misleading statement. The body can create glucose only by destroying protein and the amount it can create is limited by the buildup of toxic waste the process leaves behind. It's absolutely not the same thing as the body synthesizing vitamin A from carotene. You will be much better off eating carbohydrates, and 45% may be still too little.