Marcium Reflect V7.23825, licensed, Windows 10. Change log page announces v7.23897. I can't figure out how to download and install the update. I have the ReflectDLHF.exe.  

If you already have Reflect installed, you should be prompted to update when you launch Reflect itself, otherwise you can manually check for updates by going to Other Tasks > Check for updates.  If you want to download the full installer (which isn't actually necessary), download the Reflect Download Manager linked in this KB article, run that, and it will allow you to download the actual Reflect installer.