###General problem

two (Chrome/Web)-Extensions tried to redirect the same request. In this case

the most recently installed extension wins and all others are ignored.

uBlock (and others) consider this non-fixable on their part, as

An extension is not notified if its instruction to modify or redirect has been ignored.

###Your problem

As mentioned, it seems that you can exclude specific patterns from HTTPS Everywhere, as in

<exclusion pattern="^http://(?:\w+\.)?stack(?:exchange|overflow)\.com/users/authenticate/" />

It should be possible to exclude all wikipedia.org links, as the wikiwand extension then redirects to wikiwand.com (if that works), but wikiwand acknowledges:

There are some known problems with those extensions: Kill Evil, HTTPS Everywhere

... but not on the main conflicts list.

It seems as if wikipedia already uses https, so simply excluding wikipedia.org would not pose a problem.

General problem

two (Chrome/Web)-Extensions tried to redirect the same request. In this case

the most recently installed extension wins and all others are ignored.

uBlock (and others) consider this non-fixable on their part, as

An extension is not notified if its instruction to modify or redirect has been ignored.

Your problem

As mentioned, it seems that you can exclude specific patterns from HTTPS Everywhere, as in

<exclusion pattern="^http://(?:\w+\.)?stack(?:exchange|overflow)\.com/users/authenticate/" />

It should be possible to exclude all wikipedia.org links, as the wikiwand extension then redirects to wikiwand.com (if that works), but wikiwand acknowledges:

There are some known problems with those extensions: Kill Evil, HTTPS Everywhere

... but not on the main conflicts list.

It seems as if wikipedia already uses https, so simply excluding wikipedia.org would not pose a problem.