Table:
0
A
B
C
D
E
1
Proto-Germanic
West Germanic
Old English
German
Dutch
2
*þ
*[þ]
[θ]
/d/
/d/
3
*þ
*[đ]
[ð]
/d/
/d/
4
*đ
*d
/d/
/t/
/d/
5
*đ
*d
/d/
/t/
/d/
6
*t
*t
/t/
/s/ or /ts/
/t/

Questions and formulas:
Question: What's the Proto-Germanic when the Old English is /d/?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,C1="/d/"),1))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E6,C2:C6="/d/"),1))
Level: medium
Question: What's the Proto Germanic when then German is /s/ or /ts/?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,D1="/s/ or /ts/"),1))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E6,D2:D6="/s/ or /ts/"),1))
Level: medium
Question: What's the Dutch when then Old English is /d/?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,C1="/d/"),5))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E6,C2:C6="/d/"),5))
Level: medium
Question: What's the West Germanic when the German is /s/ or /ts/?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,D1="/s/ or /ts/"),2))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E6,D2:D6="/s/ or /ts/"),2))
Level: medium
Question: What's the Proto-Germanic when the German is /t/?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,D1="/t/"),1))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E6,D2:D6="/t/"),1))
Level: medium