No, I believe the first time Power Rangers used footage from a Sentai crossover (a tradition that had been around before PR existed) was in Power Rangers Zeo, when the "Alien Rangers" (based on Kakuranger costumes and footage) returned for a guest appearance. But if you're referring to Lost Galaxy, that was the first season that started with a whole new Ranger team from scratch rather than having a continuing cast from the previous season and just changing their costumes. So it was the first time they could really incorporate the footage from a Sentai crossover and use it the same way, as a meeting of the current and previous Ranger teams.
Yeah I think you are right.
After Zeo finished I sort of lost the series until Time Force.