At this moment of writing Timeshift (it can be any other package) can not be build. The maintainer says to downgrade vala. You will be able to build the very latest package then.
But let us be honest the latest version is sometimes not that important.
As long as you can have the application, you will settle for a version from a week or a month ago. Arch Linux is pretty fast in updating anyway.
Instead of downgrading (tutorials about that on this website) I will show you an even faster way of installing this particular package.
This will only work with the packages that ArcoLinux puts on its iso’s
When we build an iso or when you build an iso – ArcoLinuxB project – you will install the packages we have build during the last month.
Since we release a monthly iso you will always have the version of 1, 2, 3 and max 4 weeks ago.
You can always install any application coming from this website :
https://bike.seedhost.eu/arcolinux/
Navigate to the contents of this folder :
/arcolinux_repo_iso/x86_64/
Look for you application (not sig) and download the package. Double-click and install it.
Pamac might say you there is a newer version after this installation.
To get rid of that message …
Open /etc/pacman.conf with sublime-text
and add your package to this line (timeshift in this example)
IgnorePkg = timeshift
Delete the hashtag in front of the line or it will NOT be used.