I have heard back from Adobe who have confirmed the check box is how you include/exclude topics for translation. To deal with your points, use the Topic Status field as that shows in the Translation UI.

What you can do is create new Topic Status values that will tell you whatever you want. Here I have entered "Ready for Review" where the field reads "Add a new status" and clicked +. That adds it to the values below. You can add as many values as you need. Never translate, Not until next major release and so on.

Thus instead of selecting Yes/No as you would for content, you select from as many status values as you want. Thus you have more options than the simple Yes/No.
Whatever you set, then shows in the UI and to my mind that is more useful because of the multiple values.
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My site www.grainge.org includes many free Authoring and RoboHelp resources that may be of help.
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