Can't help in regards to private guides as we used a Japanese speaking one. But for the day trip to Montserrat, I can suggest checking this company out. We used them to set up a private tour for our group in 2014. Even in the pouring rain (!) which is very rare for Barcelona, we had an amazing time. The monastery setting is just amazing. The visit to the castle and lunch were lovely and our guide was very passionate about wine! I hope they are still as good as they were in 2014. https://www.castlexperience.com/en/w...rat-tapas-wine

I trust they realize that private guides are not necessary for Barcelona? Guided tours of certain sites might make sense (e.g., the Sagrada Familia, the buildings by Domench i Montaner) and some places will likely be best seen with advance reservations (e.g., Casa Battlo, flamenco performances).

It is very easy to visit Monserrat on one's own. I found this site particularly useful:
https://www.montserrat-tourist-guide...rat-train.html

Nothing like waiting until the last minute to make plans. For a private tour guide, who may be able to handle everyting for you, and your friend, check out Spanish Trails Barcelona (https://spanish-trails.com/barcelona-tours/). You can also check Barcelona Sandra Tours (https://www.barcelonasandratours.com). And if you can't connect, try Pepito Tours (Pepito Tours | Your Barcelona guide, when you need one!).