Hi,
Proper "shock" levels will not bleach your liner, but you have to be careful not to get it too high...hence the "Best Guess" table. With your CYA as high as it is, though, you're likely to have trouble getting your Cl high enough to do any good. I strongly suggest that you do partial drain/refills to lower it, if that's feasible for you.

If you have combined chlorine in your pool, then when you shock, they will lower the Cl level fairly quickly. Even if not, I don't think you're stuck with 25 ppm Cl for 2 weeks, probably more like 3-4 days....

Janet