Addon developer not willing to continue development due to allegedly no cooperation of Mozilla. Addon superfluous with browser.tabs.insertAfterCurrent being in Firefox now, and Mozilla apparently not appreciating this addon-developer for his time.

Does't work on lollipop

I'm using Android tablet. This extension does nothing. All my new tabs go to the end of the line

I think this extension only simplifies the manual inclusion of this option: "browser.tabs.insertAfterCurrent"

This can be done manually using two steps:
1. Type in the address bar: "about:config?filter=browser.tabs.insertAfterCurrent".
2. Set to "true" by double click on it.

Done.

Not working on my tablet

Does not work on Firefox for Android

It was perfect, but now it opens multiple tabs in the wrong order.
According to the author that's the way it should be, despite default Firefox behavior being different.
I can't recommend the extensions that changes something it shouldn't change, and when other alternatives available.