You're suggesting to risk everything Elsa has gained over 2+ years, with little benefit. Getting Sanne out of her cell is one thing; getting her out of the castle is another. In the state she's in, I don't know how many steps she can walk before she collapses.
Even if Mauro doesn't witness the jailbreak, other prisoners will, and may try to foil the attempt in hopes it'll shorten their sentences.