WHAT I THINK ... not what I know, which is very little ...
First, what I wrote about the person beneficiaries (like family members) of an IRA that has a charity(ies) as a cobeneficiary(ies) having to take distributions of it all within 5 years -- I'm not sure where I read that ... I think in multiple places ... I think one place was Ed Slott's 2004 book "Parlay Your IRA into a Family Fortune" ... Anyway I really don't know.
No matter what, the charities will be fine -- they will get their designated share right away, and it will be tax free to them.
One can have multiple IRA accounts (that's one of the few things I actually know). Let's say a person has two traditional IRAs -- I think if IRA #1 has charities as cobeneficiaries, then the people beneficiaries get screwed (have to take the distribution over 5 years or whatever) ON THAT PARTICULAR IRA.
If IRA#2 has just people beneficiaries (and no charity cobeneficiaries), then those people will be fine and can take RMDs over their expected life expectancy (there are tables for that), like my sister and I are doing -- on IRA#2. But I'm not sure of that.
irahelp.com was and probably is a great great resource for everything about IRAs. (I had a lot of questions back when my sister and I inherited).
Right now I don't have any charitable beneficiaries on any of my IRAs because I don't know. Not that I don't care about charities -- I gave my farm to Population Connection ( PopulationConnection.org ) in 2016 (in exchange for a charitable gift annuity). But I haven't been doing the estate planning that I should be doing.