Equipment with 20 heal can not be maged to its maximum

Normally, to mage an equipment with 20 units of a stat, for example 20 pushback damage, a pa rune is required to do the last jump from 17 to 20, as the +1 runes no longer work effectively.

Here's the thing: there exist a few items that grant 20 heal [Mazin Lyn Sandals, Nutcracker and Aermyne Cape], and the maging system is the same for the hea rune (except that it has 20 points of sink), but there does not exist a +3 heal rune. This makes it so that it is virtually impossible to reach the natural maximum of these items unless they were already crafted with it. I do not mean that it is "too hard"; the probability for it to land is borderline zero.

In the maging system, some items are harder to mage than others, but any single stat in an item can be brought to its natural maximum with a properly sized rune... except these three where it is virtually impossible.

Ideas:
1) The more immediate solution would be to create a pa hea rune (+3 heal) such that these items can be properly maged like any other item in the game. That rune would have 60 sink, which is kind of high, but that's basically a range rune (51 sink).

2) An alternative solution would be to reduce the heal of these items to 15 and put the 5 remaining points into their set bonus. This may be impossible to do retroactively though, but at least the dev team should prevent future items having more than 15 heals if this problem is not addressed. Curiously, Nutcracker is a very recent item, introduced in pandala update, so I am not sure why they keep doing it.

This is quite a specific problem, as it pertains to only three items in the whole game, but as far as I know this is the only instance of an imperfection in the design of the maging system, which is otherwise impeccable.