firstly, you are creating subflows for individual use - that not only defeats the purpose, it makes things harder to manage. In what you are doing, you may as well make your life easier and not bother copying the dashboard elements to a subflow, but instead, copy them to a new tab in the editor.
Next, I feel your pain having to change the group for each element - luckily, we introduced the ability to set a "Config Type" as an env variable for subflows.
this means, you setup your commonised view once, set the UI "group" as the Env Var, add as many subflows instances as you need - each time, setting the ui-group on the subflow env var properties ONCE (not for every UI node).
This however, is not supported by dashboard 1 (though it will may work). However, for the new Dashboard 2.0, this is supported out of the box.
Something i was toying with was showing a separate tree entries for sublfows templates that contains UI nodes - permitting user to drag-drop sort them. it was out of scope due to not knowing if the feature would be used or desired. Fortunately, this is all in the dashboard side. so once NR4 is "current", and the feature is fully released, an update to dashboard is possible at a later time.
BUT it is quite a large piece of work so not likely to drop any time soon
What MIGHT come before that ^ is exposing the sort number as a number entry field when a UI element is inside a subflow template (like we did for the sizer) - that would be much simpler to deliver and would start being useful sooner rather than later.
* If you really need to sort them, at the moment, you would have to cut them from the subflow, paste onto regular flow, sort in the sidebar, cut and re-paste/re-connect in the subflow. (or export, manually edit, import)
For me this isn't much of an issue as usually I only have one node in the subflow (a ui-template). The fact that I can't position the subflow in the group is the main issue for me.
For the requirement in this thread, however, I think the sorting within the subflow would be the issue.