I’m new to Sufferfest and am working my way through ToS (after doing FF test last Friday). Today during Fight Club, I inadvertently hit the shifter buttons and found that they are FULLY OPERATIONAL! What a pleasant surprise. Inner buttons go up-and-down through ERG and Level modes, and top buttons adjust intensity ® and gradient tilt (L). Imagine my surprise when knocking the bike out of ERG mode during a sprint.
Of course, there is an entire support page on this topic and I had to find it in a search after completing Fight Club, Wahoo Kickr Bike – Sufferfest Support