When you add a Bootstrap 4 theme to a new page, the icons for choosing a color don’t update to the actual theme’s colors. So, for instance, if I’m using Cosmo - it shows the colors in the select menu for the standard BS4 theme. Not Cosmo’s colors.
It would be helpful to web designers and graphic designers if those colors showed the actual current color for the BS4 theme - since some of them have red as a primary - for example.
I like the idea of custom theming. Particularly if it lets you save it as a user preset. I wonder if having it web based on Wappler.io instead of within Wappler is a good idea? Then you can draw people in that just want to create a custom BS theme, and it would help build brand awareness.