I also have HFTs (and SR ART resonators) on my window as well. Each of these tools serves a different purpose
1. The marigo dots damp the glass and make it more like a wall
2. The sound planks treat reflections from the glass/wall
3. The HFTs then focus the sound at the reflection points and make the glass/wall disappear
The good thing is all three are readily removable
ps my window is also an acoustically designed dual double pane setup without any parallel surfaces ...