I think the question is a bit confused. For a rabbit to be shown as a broken (a colored coat broken up by white patches), it needs to have a certain amount of color. For angoras, the minimum is 10% color/90% white, with a maximum of 75% color/30% white. For Holland Lops, the maximum amount of color is 70%, I didn't see a minimum. Broken Rex are 10-50% color. It would be very subjective when you got down to Charlie status as to whether a coat is 9% or 11% color. Tris are a subset of brokens, and aren't showable in many breeds, so this isn't so much a showing issue. Generally, for a broken to be showable, your breed has to have sanctioned brokens as an acceptable pattern, AND the base color has to be an accepted color as well. Some, like Holland Lops, have accepted tri, even though harlequin is not accepted.
I think the difficulty is in determining what makes a Charlie. Technically, it is simply a nickname given to rabbits with two broken EnEn genes (the En is code for 'English spotting', as the English Spot breed's spots come from this gene.) Since they aren't born with a genetic flag that says 'Look at me! I'm a genetic Charlie!', we need to look for clues. The first clue that you can see is the minimal spotting. But that's only a clue. It doesn't make them a Charlie. The 100% broken kits when bred to a solid is the best sign that the parent has only dominant broken genetics.
By definition, Charlies lack much color in their broken coat. It's the first clue. So, you can't have too much white/too little color to be a Charlie. You may well not have enough color to be a showable broken, that's a different issue. The Charlie issue is talking genetics, which we call genotype--En En Charlie vs. the normal broken En en (en en is a normal solid color rabbit, double recessive). The 'not enough color' issue is talking show/registration status based on appearace, called phenotype. Charlies simply lack much color, the real proof of being a Charlie is in the inability to throw any other offspring than brokens when mated to a solid.