Wrong position of sub/superscripts in math on big content

[Omikhleia]

Observed
(the square root comes from #2119, but this is orthogonal to the issue)

The exponents on "big" blocks (bracketed blocs with fractions, etc.) are really off.

Note

There's some commented out code in our implementation, let's check what restoring it does:

diff --git a/packages/math/base-elements.lua b/packages/math/base-elements.lua
index ea58071e..18af78cb 100644
--- a/packages/math/base-elements.lua
+++ b/packages/math/base-elements.lua
@@ -610,7 +610,7 @@ function elements.subscript:shape ()
       self.sub.relX = self.width + subShift
       self.sub.relY = SILE.types.length(math.max(
          constants.subscriptShiftDown * scaleDown,
-         --self.base.depth + constants.subscriptBaselineDropMin * scaleDown,
+         (self.base.depth + constants.subscriptBaselineDropMin * scaleDown):tonumber(),
          (self.sub.height - constants.subscriptTopMax * scaleDown):tonumber()
       ))
       if self:is_a(elements.underOver) or self:is_a(elements.stackbox) or self.base.largeop then
@@ -629,7 +629,7 @@ function elements.subscript:shape ()
       self.sup.relY = SILE.types.length(math.max(
          isCrampedMode(self.mode) and constants.superscriptShiftUpCramped * scaleDown
             or constants.superscriptShiftUp * scaleDown, -- or cramped
-         --self.base.height - constants.superscriptBaselineDropMax * scaleDown,
+         (self.base.height - constants.superscriptBaselineDropMax * scaleDown):tonumber(),
          (self.sup.depth + constants.superscriptBottomMin * scaleDown):tonumber()
       )) * -1
       if self:is_a(elements.underOver) or self:is_a(elements.stackbox) or self.base.largeop then

Result:

--> Maybe can we bisect why this code was commented out? It seems it was doing something more or less expected!

[Omikhleia]

Partly relates to #1799 (although the question was more general)

[Omikhleia]

Ah, maybe those lines do adverse things in inline (non-display) math:

Current:

With the commented-out code reverted: The exponent is slightly raised and moves the interline...