On November 15th, games without an age rating will disappear from the German Steam Store.
I'm not sure if mods like EIR are included, but it would be a shame. In any case, COH from 2006 has no age rating in the Steam Store!
For COH 2, an age indicator is displayed.
https://www.heise.de/news/Steam-Warum-einige-der-besten-Indie-Spiele-bald-ausgeblendet-werden-9960615.htmlThe developers of the affected games could fill out the Steam questionnaire at any time and incorporate the age rating obtained in this way into the store websites of their titles.
