Canva is very interesting, they are definitely trying to disrupt the way things have been done between designers and clients. I’m looking for a job now and in at least one listing, Canva experience is there as a desired thing! Even our parish priest is creating all his own ads in Canva for the church bulletin. No comment on the quality there :)
This sort of DIY attitude towards design seems to be the new thing, people who used to hire designers have these options that are ‘good enough’. Canva boasts almost 200 million users vs 30 million for Adobe CC. There’s a big price difference of course, but that’s still a lot of people who have convinced themselves that they can get reasonable work done in Canva. Plenty of developers out there have noticed and come up with their own DIY design platforms (Adobe Express, Penji, VistaCreate, etc)
Canva continues to improve–I just looked and they now have a video editor. There’s information there about professional PDF accessibility features like tagging and reading order. I’m sure these things are rudimentary compared to Premiere Pro and Acrobat but the Canva people are relentless at getting better.
I have no answers for you, I would hate to have to deal with Canva documents. In a way it reminds me of my most recent job where we’d get PowerPoint-designed posters to fix for print and Word-designed sales PDFs to remediate before uploading to the Web. Often the only solution was to recreate in InDesign, not sure if you have that option.