Understanding of usage field of speedj and speedl

I have used servoj for linear path and trajectory planning in task space but lagging happened at intermediate points. I have tried speedj that works perfectly for joint reaching desired joint positions. However speedj working style seem to me movej so I cannot make linear path planning with speedj. Speedl also seems to good but this cannot allow to me to make below link application.Or I couldnot handle with speedl for below link application.

My question is due to middle points lagging middle points do I have to design pid controller for servoj? Must I use another motion functions like movep or speedl with respec to my planned trajectory?

I think speedj or speedl is not suitable for this application. I will try movep function for this application. I hope that I will be successful for middle points.