If I am making dough for sweet cinnamon rolls in a bread machine how can I tell if the dough needs a little more liquid or a little more flour when the paddle is mixing it? Is there a finger test or similar?
In my experience with the kind of bread you're making, you want it fairly wet. But breadmaking is all about experience. You need to get familiar with the dough and see what works, then try altering your recipe and see if it's better or worse. Change just one variable at a time, and if possible, bracket (make your rolls with what the recipe calls for, then make a batch with 1/4 cup more water and a batch with 1/4 cup less water).
I don't know about your particular recipe, but in traditional breadmaking it's possible to make good breads with the same recipe with widely varying hydration. I recently saw FoodGeek make loaves from 100-120% hydration. https://www.youtube.com/watch?v=2XCbonAQkWU.
The video is instructive because it also shows the effect the three different hydration levels have on the loaves.
The other thing I'll say is that often you can knead dough successfully with higher amounts of water than you think. You just have to be patient. Once the gluten network gets strong enough the dough is surprisingly workable.
Just remember that all those batches of cinnamon rolls are going to be delicious even if they're not perfect. So share with friends and have fun with it.