I'm new to this idea but did a bit of searching. The origin of this idea of "genetic entropy" appears to be a guy named John Sanford. He is also the author of the "waiting time problem" you reference. The principal author of the other reference you cite is Michael Behe. Both of these guys are ardent creationists. This means they have an agenda. Good science is the product of good questions, it does not result from attempts to support preconceived notions. This especially applies to religious ideas since they are generally strongly held.
Further research into the "genetic entropy" idea suggests that Sanford has basically repackaged an older idea but with a decidely creationist slant. That original idea is termed Muller's ratchet. https://en.wikipedia.org/wiki/Muller%27s_ratchet
The conclusion of Hermann Muller, inherient in Muller's ratchet, is that his concept supports the rise and importance of sexual reproduction. I find no mention of creationism, this seems to be Sanford's addition to bolster his agenda.
If you really want to delve deeper into the flaws in the arguments of these two creationists:https://letterstocreationists.wordpress.com/stan-4/ This site contains an extensive list of links to rebuttals to the claims of these two men.