New rules for prolonged actions?

[trystero]

It would be great with some rule around failure for things like swimming Across the Anduin or scaling cliff walls.

The tables Jon posted from the revised rules cover both "Swimming across a wide river" and "a very dangerous climb", and the rules already cover both drowning and falling as sources of harm, so I think you're set there.

[aramis]

There is a table of possible outcomes; it's not hard and fast rules but suggestions for how to handle failing prolonged tests (since prolonged tests can be retried).

It's a demonstration that both major interpretations of 1E are correct - one failure can end the prolonged task, or can be just a time penalty, as desired.

The "One failure can end it" is justified by the general prohibition on retries, a couple pages earlier in 1E LMB.
The "Failure is just a time penalty" crowd claim that it is a wholesale exception. The support for this view is actually not in the rules, but in the sample adventure.

Looks like both are correct - in part. (I fell on the one failure usually ends it end of that argument.)