Oooh, don't do that!
Yes, you need the right strings. I never had one of the SC EFS sets, but yes, it is very different from standard guitalele strings. You want to start with a "bari tune tenor" dGBE set for the top 4 and then find the right ones for E4/A4 on the bottom.
If you want to try reentrant guitalele, G to G is easier to come by, especially for tenor scale.
Another fine video by the Doctor. That is a very cramped fretboard on the Yamaha GL-1 guitalele. Dr. Bekken makes it look easy to move those chords right up the neck.