If there is some precaution to take, it is mentioned in the owner's manual.
Generally to shift into H4 or L4 you should be rolling very slowly, like 2km/h to 5 km/h, the system would would not work if you try doing this at 0 km/h.
In the newer models, you can shift H2 to H4 and vice versa at upto 100 km/h, I'm not sure if the advised speed is 2 km/h upto 100 km/h or it would shift even at standstill.
Also not sure about H4-L4 and L4-H4 selection. You could check it on 3 km/h and update.