Unfortunately, I don’t know WPBakery Page Builder.
The WooCommerce Custom Tabs plugin editor fields are built from standard WordPress editors. These editors can be modified by other plugins. If WPBakery Page Builder modifies all WordPress editors generally, the Custom Tab editor fields also change. So it’s up to Page Builder to see how generally they integrate with WordPress and other plugins that use generic WordPress elements.
If you see that the custom tab editor fields have not been modified, then presumably the editor fields are not modified in general by WPBakery Page Builder.
Or, alternatively, if you can use WPBakery Page Builder to create small contents with it’s own editor that they can be inserted anywhere, so you can insert these contents into the tabs. (for example Elementor Page Builder can do it, using small templates.)