Development for manga focused features are already being discussed and piece by piece for possible implementation.
Progress and development are mostly updated by @tiar on the respective discussion threads.
you can participate in those in discussions in the following thread;
Comic Panel Tools - Feature Request by Tiar (developer)]
[Comic Work flow discussion] - (Comic workflow - general ideas and feature requests (including long webcomics!)) also being monitored by one of the official devs]
One of our pain points for example is the text tool which is now also being worked on after a painful overhaul.
Feel free to drop by those threads and add your piece and suggestion.
Due note that this is big project being undertaken and considered but that thread is monitored by an official dev interested in implementing it.