Fortunately the new package pdfmanagement allows using PDF management without tagging, see ltnews42 (well, I haven't found out myself: https://github.com/latex3/pdfresources/issues/101 ): \RequirePackage{pdfmanagement} \SetKeys[document/metadata]{lang=de-DE,pdfstandard=A-2b} So if anybody stumbles across the same issue, there is a solution.
Newest \DocumentMetadata overwrites \@startsection
Package array Error: Illegal pream-token (\sigalign): `c' used.
https://github.com/latex3/babel/issues/134
Well, babel development is under the roof of the l3 project: https://github.com/latex3/babel So I guess the babel maintainer will already know.
It was a bug in Emacs, see here: http://lists.gnu.org/archive/html/bug-gnu-emacs/2014-11/msg01219.html...
ShellExecute fails