Yes, 2017-11-29 was the last update. So sorry it's so far behind, but still better than the 2009 default version.
The mirror I setup was the backup plan in case the site ever went down. It seems http://www.istaria.info is in a weird state.
Surprisingly http://hcc.reclamation.dk/?tag=files still shows the program. But even if that site should ever go down, all the mirrored files are at https://istariareference.com/mirror or https://istariareference.com/mirror/hcc_v2.30.exe for the same .exe file on that .dk domain.
The updates used to come down from istaria.info, so since that site isn't working correctly, then simply replacing/updating the Config.xml file (also on mirror site as https://istariareference.com/mirror/Config.xml ) will let the Update button work to show any new updates.
All archived updates are at https://istariareference.com/mirror/...dates-Archive/ with exception to 2017-11-29 which is on the main mirror directory https://istariareference.com/mirror . The very last update has to stay in this folder for the update button (in HCC) to work correctly.