Kia ora Julian,
For fields in Totara that have the Weka Editor enabled, there's a "layout" option, but it is currently very limited, doesn't have table-like semantic information for assistive technology, and may not meet your use case - but is an option to play around with.
For example:
Column 1
Column 2
Column 3
It would be great if you're able to add this request for better controls for content formatting as a Canny request, and if you can note that you have accessibility requirements as well as the general functionality requirement, that will help us to build a case to make richer improvements.
Cheers, Dave