Sick Japanese aucuba

Hello

I have a very sick Japanese aucuba: many black leaves and branches, lots of dead wood and almost no new leaves. In comparison, I have a second one, almost unaffected, which seems to be doing well, with lots of new leaves and small flowers.

A Google search indicated a cryptogamic disease and suggested cutting off the affected branches and leaves. So I began this surgery (or rather butchery) (second photo). But given the scale of the task, I'm wondering whether it wouldn't be more effective to cut it back considerably.

Do you have any advice on how to prevent the death of the first and protect the health of the second?

I live in France

Thank you!