I'm still interested in Automator solutions
Use the 'Run AppleScript' action and paste my code in 😉
In all seriousness, Automator is pretty good at driving workflows when there are clear Actions that meet your needs (like the "Get Current Webpage from Safari" action). As soon as you step out of that comfort zone into areas where there isn't a specific Action (e.g. "open this URL in Chrome"), Automator loses a lot of its appeal. The closest you can get is opening a URL in the default browser, which is likely to be Safari in your scenario.
Unfortunately, creating new actions is beyond the scope of most users, and therein lies the problem.
I get hung up on things like "make new tab at end of tabs of window 1" where the language is simple, but the syntax is very specific. How can I learn these things about AppleScript?
A lot of this comes from practice and experience. 😟
The dictionary does a fair job of telling you what commands/objects the application understands, but developers rarely include practical examples of how to use them.
In this case, even though I've never scripted Chrome before, I knew that 'make new tab' was probably not going to work - it needs a location as to where to make it. Since tabs are elements of a window (at least as far as Chrome is concerned) I knew that it had to be associated with a window somehow, and since a window already has a list of tabs it just seems easier/more logical to add the new tab at the end of the current tabs.
So it's largely a logical progression once you understand how the basic components fit together, but that understanding only comes with time and practice (and asking other people, too, I guess 🙂 )