cascading dropdown with 2 values to prepopulate (also in Quip)

Hi all,

My name is Monika from Germany. I am hoping someone can help with a formula and possibly with Quip conversion.

I have created a cascading dropdown in Excel on sheet Selection. It reads from sheet DD. I have 2 issues:

1) On two occasions, there is only one sub-selection possible, so I would like to adjust the formula, that if the selection is made, it prepopulates the corresponding value in column M, i.e., when "N/A (comment)" is selected in column L, "N/A (comment)" is automatically filled in in column M. I tried a bunch of IFS and IF(ANDs but everything fails.

2) When it works, is there a way to put that into a Quip? The formula that works in Excel, isn't recognized in Quip. Maybe other functions would accomplish that? Quip seems very limited.

Any help would be much appreciated.