Using the example from https://www.openhab.org/docs/ui/sitemaps.html#element-type-buttongrid:
(the app doesn't support F7 icons, so it doesn't look exactly the same).

Your screenshot looks good and you use the text when encountering an unsupported icon, as expected.
In my Basic UI PR, you have an example with 12 buttongrid elements, each with a different number of columns (from 1 to 12 columns). It could be interesting to check your implementation with such a sitemap. Note that on a phone,I do not render more than 4 columns (8 on tablet(. Do you have a limit ?

I use the same hard limit as for the regular switch with mappings: Based on screen size 4, 5, 6 or 8 columns.