Hi Rover,
Chromecasting is now working beautifully from the sideloaded Android App. 100% reliable picture on all channels, including RTE 1 HD and RTE 2 HD on my Chromecast 2.
The Fire TV box has become a lot better since those changes were made. However, there are still frequent glitches and occasional freezing, particularly in the first minutes of loading a channel, but also intermittently afterwards. This tends to make me switch to the Chromecast streams, which work flawlessly. This is a pity as the Fire TV box is such a great platform for iBox.
I tested over several days on the Fire TV, but those two channels remain problematic (RTE 1HD, RTE 2 HD). Would be great if it could be tweaked a little more.
All the best,
Umby