I see a lot of problems launching/landing from an eighth floor balcony.
- Magnetic interference
- Loss of satellite reception switching it from GPS to Atti mode causing drift at a critical time
- Neighbors upset about drone flying by their windows
- Wind turbulence around building
- You would need to reset the homepoint away from your balcony each time
Seriously, the risk does not seem worth it. Your pictures show you are on the water so if there were a mishap the odds are good that's where it will end up.
RTH works the same (or close enough) in Go 4 and Litchi, in that it would fly back to above the homepoint and then descend. I guess you could land it in a convenient spot, reset the homepoint there, and takeoff again.
If you go for it, get a set of prop guards and post the results.