Actually, Li Pan has been forcibly transforming using the silver key combined with the handkerchief, and every time, he only manages to break one of Mr. Xian's talismans. That alone has been enough to allow him to strut around this plane with impunity, easily squashing monsters left and right.
He himself is very curious. If he could undo the remaining seals, he wonders just how powerful the handkerchief transformation could be.
Since his personal cultivation has hit a bottleneck anyway, he might as well seek new approaches, such as consulting language experts like 01044 from Otherworld. Perhaps they could come up with some new tricks.
After all, there are just too damn many talismans in the Supreme True Pavilion. If he could exchange one word for one key, he wouldn't need to grind missions anymore.