Hi, thanks for the input!
I will update undergrounds and splitters to be unlocked at the beginning / with Really Basic Logistics if AAI Industry is installed, so that progression is not broken.
However, I think I'll leave lumber and treated wooden planks unaffected, as frankly both fill a similar role. Lumber in my mods is considered treated wood (even though I didn't add a treatment chemical, that simply made progression with vanilla Factorio too complicated). And that mod uses sawblades in the recipes for treated wood, so I think it'd be best for that mod to handle that compatibility and either make treatment a second step, or wholesale replace my "lumber" with "treated wood planks". I'll post over there to share my input once I upload this change :)
I'm glad you like my mod and that it fits well with the amator phasma modset!