We could indeed do that, but first you would need to use a single flex widget with the whole 10 icons in it, instead of two widgets with 5 in each.
But I think the flex widget is too complicated for what you are doing.
The easiest way would be to use the WordPress gallery.
Use Add media > Create Gallery > Select ALL your icons > Create gallery > set your 5 columns and insert
That by default will create 2 rows of 5 columns on desktop, and 4 rows of 3 columns on mobile.
If you want a different number, we can then give you the CSS to customize it