Recently I had an issue with the mod not entirely working together with Shoulder Surfing Reloaded, the spyglass would render as a solid glass texture. That issue has now been fixed, as you can see here: Exopandora/ShoulderSurfing#165.

However, in the process of fixing the aforementioned bug, the author of Shoulder Surfing Reloaded noted that due to Spyglass Improvements completely cancelling MouseHandler.turnPlayer you can't move your mouse while looking through the spyglass in third person. They also suggested a couple of potential solutions which you can see here: Exopandora/ShoulderSurfing#165 (comment).

The issue was resolved on their side Exopandora/ShoulderSurfing#165 (comment), but I'll keep this open in case you'd still like to implement the change.

Closed as fixed in 1.5.3