Tweaking the fraction feature code

I am not sure if this is correct forum for this, but I figured at least someone might be able to point me in the right direction. I have imported the Tal Leming feature code from the OpenType cookbook, and created all the necessary glyphs to run it (it looks really good), but the issue that I have is that all of the numerator and denominator figures have been spaced so that they kern very nicely around the fraction bar, looking just as sharp as the precomposed fraction glyphs already created. This works great for single digit numerator/denominator fractions, but as soon as you add multiple digits to either the numerator or denominator their kerning is now terrible. I could space them nicely as individual figures, but then the fractions created will not have that nice crisp kerning around the fraction bar. My question is whether anyone else has addressed this issue, and what their work around/code solution was. I'm assuming that the code to correct it must either affect the figures or the fraction bar, but I'm not experienced enough to know which would be the more effective/elegant/practical approach, let alone writing the code correctly. Cheers for any advice/suggestions/solutions.

Space the numerators and denominators like normal glyphs.
Kern them to the solidus.
Kern them to each other, if necessary.

Thank you for the response. I get it, I think. Address two different problems with the processes for addressing those issues, rather than conflate the code of one problem with the "solution" for the other. Cheers. Now to get the kerning part right!