Do we know how I can download a slightly older version of Aj.js (1.8.0)?
Adobe only maintains the 2 latest versions of the at.js 1.x and 2.x for downloading. You can find the download API instructions here: https://docs.adobe.com/content/help/en/target/using/implement-target/client-side/deploy-at-js/implem...
You can find the most recent 2 versions of the at.js 1.x and 2.x here: https://docs.adobe.com/content/help/en/target/using/implement-target/client-side/target-atjs-version...
So currently, you can download at.js 1.8.1 but not the 1.8.0 via the download API. The latest version of 1.x and 2.x is of course available from the Target interface as well. Hope that helps.