See inline below and attached. If exporting to PDF the first table gets a prefix of "ced!10" and the second is the pale red highlight I was wanting.
Here are the important lines in the LaTeX buffer export:
\(\left[\begin{array}{>{\cocumncococ{ced!10}}c|ccc|ccc}
vs.
\(\left[\begin{array}{a|ccc|ccc}
This latter only works because in my header I have
\newcolumntype{a}{>{\columncolor{red!10}}c}
I'm not sure I'm reading the original issue, the patch, or the surrounding code right, but is it possible the [lr]->c substitution was intended for the case where no :align was provided by the author and org generated the alignment automatically? If so, would it be appropriate to just move the substitution to the ";; Extract column groups and alignment ..." block in org-latex--align-string, which is to say the case (if I'm reading correctly) where the author has not provided an override?
ox-latex.el-3154-(defun org-latex--align-string (table info)
ox-latex.el-3155- "Return an appropriate LaTeX alignment string.
ox-latex.el-3156-TABLE is the considered table. INFO is a plist used as
ox-latex.el-3157-a communication channel."
ox-latex.el:3158: (or (org-export-read-attribute :attr_latex table :align)
ox-latex.el-3159- (let (align)
ox-latex.el-3160- ;; Extract column groups and alignment from first (non-rule)
Org file to demonstrate problem and workaround:
#+latex_header: \usepackage{xcolor}
#+latex_header: \usepackage{colortbl}
* Non-Working Example
#+ATTR_LaTeX: :mode inline-math :environment array
#+attr_latex: :math-prefix \left[ :math-suffix \right]
#+attr_latex: :align >{\columncolor{red!10}}c|ccc|ccc
| | | * | * | | |
| * | | | * | | |
| \hline* | | | | * | |
| | | | | * | * |
* Working Example
Just define a column type that doesn't use the characters 'l' or 'r'
#+latex_header: \newcolumntype{a}{>{\columncolor{red!10}}c}
#+ATTR_LaTeX: :mode inline-math :environment array
#+attr_latex: :math-prefix \left[ :math-suffix \right]
#+attr_latex: :align a|ccc|ccc
| | | * | * | | |
| * | | | * | | |
| \hline* | | | | * | |
| | | | | * | * |
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