I wonder if I may be of help here...

Derailers especially ones with the 2:1 pull ratio (Shimano, Microshift) require really high accuracy to match up the derailer with the shifter. Along the way there are a few places where things can go wrong.

So, if you are experiencing clicking in top and bottom gears but it seems OK elsewhere, well the conclusion is fairly straightforward that the pull ratio is a bit off. Either it pulls too little or too much, resulting in the behaviour you see. It matches up with most gears but the extremes are out.

How to fix this: The trick is to reposition the derailer cable under the pinch bolt. Loosen the pinch bolt holding the cable and reposition the cable either further way from the bolt shaft or right up against it. Putting the cable right against the bolt will increase pull, and moving it a bit to the edge decreases pull.

To find out which case is yours, shift to and fro between top and the next gear next to it. In one direction it will be hesitant and the other direction it will be quick. If it is hesitant to go to top gear, it needs more pull - move the cable right up against the pinch bolt. If it is hesitant to move out of top gear, it needs less pull, so move the cable away from the bolt shaft.

I hope this is clear enough.

One final thing to keep in mind - Novas come with absolute bottom of the range equipment. To expect perfect performance from less-than-entry-level equipment is unrealistic.