Popped in really quick (:/ so little time around these days). Just thought that I would mention something.
The initial _DS_MENU.dat is used SPECIFICALLY for just booting and redirecting to a different file. Nothing else is required of it and thus there is no real "other functions" to it (no need for themes, language, font, cheats, etc.). To make things simple to understand, why would you need to update it?
Optimally, it would be best to find the smallest distribution of Wood for the R4iGold with autoboot (likely the oldest distribution) and take the _DS_MENU.dat from there, hex edit it, and use that. The updated WoodR4.nds is placed wherever and run when needed.