Ah, ok...the context helps. Apologies if I cover anything you already know, but I figure it's best not to miss anything. I haven't done this yet, so we're just discussing theory anyway 
So, the Planner hierarchy is Plan > Bucket > Task(s) right (and each task can be assigned to multiple people or none at all)? And my understanding of what you want to do is create a bunch of tasks in one bucket (almost like a template) and then copy those into other buckets within the same plan. Good so far?
The second writeup you link to does this, but is triggered by "creating a new task" as you mention in your original post. Your challenge is you want to bulk copy the tasks all at once to the other bucket, so you'll either need a manual trigger (button) or a recurrence (schedule). When the trigger was originally when a new task is created, you had all of the task info from the trigger. Now that we're shifting the trigger to something else, we still need to get the task details.
To do this, our next step after the trigger (button or schedule) would be to List Tasks (not "Get Task" as that is for a distinct/singular task, and we want a bunch), and then from there we can "copy" them into the new bucket by using "Create Task" and just assigning the new bucket ID. 
If the FROM bucket and the TO buckets are always the same, then you can skip the steps where he gets the names and stuff (this actually makes things wayyyy easier) and just used a static ID for each. Here's where things get a little weird:
Because you're listing ALL of the tasks in a plan, you want to filter out only the ones in a certain bucket (your template), right? So you'll want to set a "Condition" to look for the bucket ID of your template bucket, but to get that ID, create a task in your template bucket that you'll recognize and run your flow just as it is above. Then go back to the output data and find the line that has that task name...It will look like "title": "Create Demo Surveys" - Right above that is "bucketId": "ywYgy7M-80qgCoGbVXmSAmQAD9kB" and that bit of gibberish is your Template Bucket ID.
So now, you can add a condition to look for that bucket ID...but because there are multiple tasks, Flow will automatically put this in an "Apply to Each" loop. Don't freak out, this is totally a good thing. It's going down your list of tasks and asking "Is this in the bucket I want?" and then acting from there.
When you use "Condition" it branches into a "Yes" or a "No", so the "Yes" path would be "Create a new task" and the "No" path could just be a terminate.
Note that I chose a totally different Plan, and then the Bucket ID is a clever drop-down with the friendly display name (no need for the TO bucket gibberish ID).
Now, if you decide you want to add the Assigned User Ids, you totally can...but remember that because each task can have multiple assigned to users, it will create another Apply to Each loop within the first one. And that may get weird.
But try that out so far, and see if that gets you closer. I don't want to go too far down the wrong direction, so let us know how things pan out.
-Ed-
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