Those two are not dynamic settings, I think you can only set them in the elasticsearch.yaml, which requires restart.
Sadly, what you describe makes sense. The current transport ping mechanism acts as a keep-alive to not have connections drop which may happen in some situations. But it does not wait for a response to the ping nor does it support a timeout, which means that if the other side is down, this mechanism does not help with detecting the failure quicker than before.
Thanks for your feedback, we will need to improve the ping mechanism like I described in the issue that I linked above.
Cheers
Luca