During summer, I teleported away from my base that has a fingomatic. I returned using another Backtrek watch and many of the structures inside of the fingomatic's range were burned. I did not hear or see any smoldering happening before I teleported away. The fingomatic had plenty of fuel and was on.
1) Be Wanda.
2) Be in Summer.
3) Have a fingomatic near flammable objects or structures.
4) Create 2 Backtrek watches. One anchored near the flingomatic (mine was anchored within it's range). Have the other one anchored somewhere far from the base (mine was anchored at the Atrium biome).
5) Use the Backtrek watch to teleport away from the flingomatic. Then use the other one to return. I waited maybe about 1 minutes until I went back home where the flingomatic was stationed.