Bibliography order does not match generated label naming for twin bib entries

Question

I have to use the bst file provided by the university for my work which is an edited IEEEtranSN.bst. Unfortunately, the generated order of ambiguous entries (by attaching a letter) does not match the actual naming, i.e., I expect [author, 2010a] to appear before [author, 2010b] in the bibliography.

This is probably a problem in the sorting defined in the bst file. I would prefer changing the .bst instead of manually changing the bib entries since the real bibliography I am using is quite long.

Minimal code example, adopted from a related question using the separately uploaded bst file:

\documentclass[12pt, a4paper, openright, twoside]{book}

\begin{filecontents*}{\jobname.bib}
@inproceedings{landgren2016distributed,
  title={{\noopsort{A}{On}} distributed cooperative decision-making in multiarmed bandits},
  author={Landgren, Peter and Srivastava, Vaibhav and Leonard, Naomi Ehrich},
  booktitle={Control Conference (ECC), 2016 European},
  pages={243--248},
  year={2016},
  month=may,
  organization={IEEE}
}

@inproceedings{landgren2016bdistributed,
  title={{\noopsort{B}{Distributed}} cooperative decision-making in multiarmed bandits: Frequentist and Bayesian algorithms},
  author={Landgren, Peter and Srivastava, Vaibhav and Leonard, Naomi Ehrich},
  booktitle={Decision and Control (CDC), 2016 IEEE 55th Conference on},
  pages={167--172},
  year={2016},
  month=sep,
  organization={IEEE}
}
\end{filecontents*}

\begin{document}

\nocite{landgren2016distributed}
\nocite{landgren2016bdistributed}

\bibliography{\jobname}
\bibliographystyle{IEEEtranSN_edited}

% \bibliography{./biliography.bib}


\end{document}

Here, I expected the order to be equivalent to the label order, listing the extended cites [author, 2016a] before [author, 2016b] first.

Do you have an idea what specific changes are needed in the bst to achieve this?

Thanks in advance!