This does not look like <guelyeñ> to me, but that's how Ernault read it. <guelreñ>?

However, this is not otherwise how this type of verb develops. I MBret. and much of ModBret. the alternation in such verbs is preserved and when we see generalization of one of the allomorphs, it is the one without i-affection, as seen in K(T) digoriñ. alongside the usual digeriñ, digor-.