Compile this MWE with LuaLaTeX
\documentclass{article}
\usepackage{libertinus}
\begin{document}
\(w_j q^j\)
\end{document}
The result is:
IMHO, the space between "w" and its subscript "j" is too much, while there is nearly no space between "j" and the following base symbol "q". It looks more like the "j" would belong to the next base symbol than to its true base symbol.
The result is the same for XeLaTeX.
Of course, I understand why it happens. If ones draws the bounding boxes around the "w" and the "j", one can see that the bounding boxes are actually touching each other. (The upper right end of the last stem of the "w" and the lower left serif of the "j" are vertically aligned.) But IMHO, the bounding boxes should overlap due to the special shape of w and j.
a) Is this a bug in the font, because the kerning table is wrong for this pair? Should it be reported to the Libertinus project? Or is it a bug in LuaLaTex?
b) Is there a quick and dirty workaround that can be applied on the document level such that for all occurrences of this special combination of glyphs a manually adjusted kerning is applied? (I probably cannot wait with my manuscript until the bug is fixed upstreams.)
