In Western European siddurim there are two pesukim before Kaddish Tiskabal. One from במדבר and one from תהלים. They are present in the Rödelheim/Sfas Emes, the Seligman Baer (page 150 in the pdf), and Sefas Yisroel (page 18 in the pdf), among others. My question about these pesukim is twofold.
- What is the source (if any) for saying these pesukim?
- Who says them? The kehila, or the shaliach tzibor, or both together?
Edit: None of the siddurim above have any instructions about these pesukim that I can find.