Short answer: Soon.
Less-short answer: Pretty soon.
Long answer: There are about three dozen or so scripts that are affected by changes in iTunes 12.2. I'm updating those first and those updates should be finished within a couple of weeks. You may have noticed a number of updates in the past two weeks already. (Apple did not make a pre-release version of iTunes 12.2 available to developers, unlike the El Capitan developer releases. So I found out about changes when you did.)
Many other scripts need to be fixed for El Capitan specifically, but those are lower priority since 10.11 won't be officially released until the Fall. However, when I have had the opportunity, I've included fixes for 10.11 when making changes for the latest iTunes. But, generally, if you are using the El Capitan Public Beta, don't expect many scripts to be updated for at least a few weeks, until the scripts requiring updates for iTunes 12.2+ are updated.
As always, thanks for your support and patience.
Multi-Item Edit is an applet that acts as an alternative to iTunes' "Get Info" editing panel:
You can read more about it on its product page, where there's also a quick YouTube video explaining how it goes.
This latest version fixes a problem with changing Last Played and Last Skipped dates in single-edit mode; fixes a logic issue with auto-setting checkboxes; worksaround issue whereby iTunes Match tracks might be ignored; fixes an issue with toggling Information Tracking; and has preliminary support for OS X 10.11 (El Capitan) beta.
Multi-Item Edit is free to try for ten days, $1.99 thereafter.
As I pointed out last year when the first Yosemite beta was released:
I make no guarantees as to the reliablity of any software authored by me when operated under a pre-official-release beta version of the operating system.
10.11/El Capitan-compatible software will be clearly labeled as such if and when it is actually compatible. Otherwise, don't presume any script or app is compatible with El Capitan at all until the official release date in the Fall.