It looks like the csquotes package does not allow nested citations such as
\foreignblockcquote{foreign language}[pre-note]
[post-note with citation \textcite{key2}]
{key1}[punctuation]{quoted text}
The error message is
Package biblatex error: nested citation command. See the biblatex package document for explanation
but I could not find anything in the csquotes and biblatex user guides. Originally, I was interested in using the \textcite command developed by Audrey in
biblatex footcite and footnote
This question may also be related to Is it possible to make automatic multiple citations with csquotes and biblatex?
