I can't replicate your error. I've made two iPad edits on the page you mentioned, one in source mode, one in the new VisualEditor. You can find them here: http://tardis.wikia.com/index.php?title=The_Birthday_Boy_%28comic_story%29&diff=1639335&oldid=1639333
The one on the left was made in source; the one on the right was done in the VE. Keyboard triggered fine on both occasions. Safari for iPad is definitely a supported browser for the VE, and for Wikia in general.
(I also don't know what you mean by "improved source". Source is source — it hasn't been improved. Are you maybe meaning the source editor under the "more" menu? If so, you're still within VisualEditor and aren't using anything "improved". If anything, that's "source lite", with many features of source missing.)
In order to try to help you, I'd need to know a few more details:
- What is your iOS version?
- Were you using Safari? If so, what version number? If not, what browser were you using?
- Have you done a full reboot of your machine recently? If not, please hold down the Home and Sleep/Wake buttons — i.e. the one on the front and the one on the top — simultaneously until your machine actually powers down. Then, restart your machine and come back to a previously-problematic page and try to edit again.
- Is your machine nearing its storage capacity? If so, consider dumping some of your stuff so that you have at least 1GB free space.