Thank you for your comments. I want to comment on that: On Tue, 31 Jan 2017 09:26:53 +0000 (UTC), notify@aur.archlinux.org wrote about "[PRQ#7395] Deletion Request for palemoon-26":
trav90 [1] filed a deletion request for palemoon-26 [2]:
The build configuration used by this package does not produce binaries that are acceptable for official branding and therefore are in violation of the Pale Moon Redistribution License located at https://www.palemoon.org/redist.shtml.
Since this package compiles locally, no binaries will be redistributed, so there should be no problem there. Problems would arise if users who compiled the binaries would redistribute them.
Also, this is an old version that is no longer supported by the Pale Moon team. Add-ons using the Jetpack SDK will work again in the next (supported) release of Pale Moon, making this package unnecessary.
So this package might stay until the next release of palemoon is out.