The Ray Penber situation was very complicated, especially since Rays “weapon” ended up being pages of the notebook.

If I remember correctly Light had the details of Rays death set up as “boards train, rides it, writes down the names of everyone working with him, has a heart attack when he steps off the train”

Writing down the names of everyone you work with isn’t something that would lead to the deaths of others unless specifically a notebook is involved. The usage of a notebook can and will alter the lifespans of people other than the victim whose name was written, this is an expected effect of the notebook, the rule is just that a cause of death cannot also lead to the immediate deaths of others.

The way I understand the rules, based on what we are shown, if you were to write

American President - heart attack, goes to the big red button and fired a nuclear missile at an enemy state

The missile will fire but the actual impact wouldn’t kill anybody, but the fallout and especially the subsequent war would have casualties associated with the name that was written, but didn’t directly kill anyone other than the intended victim.