For the guy on the orange path. He switches from his left turn signal to his right turn signal just before he switches lanes. A car moves about 29 feet per second at 20 mph and about 37 feet per second at 25 mph so he MIGHT show one flash before he is off the whole roundabout. Who is supposed to benefit from that signal? That is if somebody felt like trusting a turn signal to begin with.
The guy waiting to enter the roundabout will see the signal, it's usually more than one flash, and know it's safe to enter.