I would not use resource strings for this purpose. Like you mentioned changing it to support WYSIWYG is quite challenging and I would not prefer to make modifications to Kentico.
There are a couple of directions that I would consider. One would be to leverage Linked pages and for example create a folder in the content tree that contains all the original items.
In the case that you would require Page builder widgets then you might find it useful to look at the Shareable content feature in: https://github.com/HBSTech/Kentico13CoreBaseline
Hope this helps!