Editing interfaces for AAC devices are hard
Editing interfaces for AAC devices are hard. Much much harder than the speech interfaces. It’s simple to write an AAC device that just makes noises (and many of the apps listed on Apps4AAC are exactly that), it’s much much harder to write a decent editing interface.
So it’s hard to do. It’s particularly hard to do well. One reason is because most people (who in the particular context we are looking at are parents, carers, and so on) who modify the content on AAC devices have low levels of IT literacy: so the design has to be friendly, intuitive, and ‘risk-free’. If users think they might potentially break a vitial device then they are unlikely to pick it up at all.