We don’t really advocate it’s usage, we just provide it as an option for those that are inclined to use it. A lot of the systems I’ve used don’t even go that far and you’re limited to plain text.
Long term it would be better to use markdown, but even with that the support for table formatting is not going to be simple.
In the mean time if you create a draft invoice with the format you need you can just copy use that as a template and copy it. Or store the invoice line within the inventory system.