For C1 and sharpening, my understanding is that the defaults shown are specific to the lens and camera combo, so that a "sharpening amount" of 185 for an IQ3100T+35mm would be different under the covers than a 185 for the IQ3100T+150mm combo. For that reason, I tend to leave it at the defaults and then evaluate image by image and change if needed.
For custom settings, it's limited to 3 custom banks and only for settings that can be done in the XF itself. I've not found a way to store back+XF combinations, for example if I wanted to use a particular file type or ISO setting. For the IQ3/XF, this information is
here if you haven't already found it. (Search on Save Custom Presets in the doc)
Unfortunately, nothing to add on the trigger issue you're seeing.
Cheers,
Ray