I used to have a age group student with Babolat Storm Limited and he also had difficulties with strings for this a bit similar racket to yours. I tried to help him out also. He tried around 20 different set ups, full poly, hybrid, multi, syngut and hybrids, with strings from the big brands, with tension from 48 to 58.
Difficult to find something that give both control, feel and power....always something missing.
I met him last week at a tournament and asked him. Now he has found something he is happy with : Babolat adrenaline, 51 lbs, two knots. He is very string sensitive for being 13 years old.
He hits flat (higher balls) and topspin (lower balls), slice serve, medium paced rhs.
Another tip would be sg main and poly cross, that is what i found for my Wilson pro staff tour, a bit similar to your stick as well. I have Gosen OG or better Prince sgd in mains at 55, and Isospeed baseline or better Prince tour at 51 for the crosses. Great feel, big sweetspot, power and control.
Issue is what kind of stringbedstiffness (SBS) you prefer (soft, medium, firm, very firm). The numbers above are for Medium sbs a bit on the soft side. If the ball go long with that set up, just up the tension on both w 2 for each meter ball go long when you go for power on a rather hard incoming ball.