Transcription and back-translation by Lily Kahn, Lecturer in Hebrew, UCL
If great (lit: high) virtues are beautiful,
Your son-in-law’s blackness is full of (lit: with) charm.
(Note: In Yiddish this is a rhyming couplet.)
Note: this Yiddish translation is written in the Soviet Yiddish orthography, which differs to a certain extent from Standard Yiddish orthography.
... all I know is that he was a Soviet Yiddish folklorist; little is known about his life but he translated nine Shakespeare plays into Yiddish with support from the Soviet state publishing house. I haven't been able to find the rest of his translations yet ...