Assuming DOSBox's built-in layouts are related to FreeDOS (as indicated in the forums), then FreeDOS has added more Layouts and Charsets after DOSBox' last release. Can you include the latest FreeDOS Layouts and Charsets in DOSBox for the planned 0.75 release?
If it helps, here are links to the aforementioned latest files. At the bottom of both of them there are download links:
Last edit: lwc 2020-02-08