Hi there!

I have answered this on a pro ticket, but i will add here some info about it !

So, this is a good question, and a good idea!

But, for this to be possible, i will have to see with Falang developer to know what could be done in such a case.
As Joomla 3.7 will be released with a new custom fields system (but only for Joomla core components, not for iCagenda), i think the developer of Falang will (or already have!) find a solution in its own extension code to enable this possibility.

For today, not enough time to put my head on this, but i set it in my todo list! (with other improvements planned for Falang translation of iCagenda)

Best regards,
Cyril