If your EC is on time, super easy. with a few minutes delay it could be challenging. Tip: check the tracks and also the formation of the trains on sbb.ch (at the day of travel)

with googling “plan bahnhof basel plakat” you can get a overview map of basel sbb. so you can plan in which sector it is best to exit the train to be at the passage (if you need to change the platforms)

thank you very much for the very important information you have provided me! They are really very useful to me!

Btw if you want to avoid the ripoff reservation fee you can also take the regional train till Lugano and then change to the EC.

Somehow the regional train is even faster. But Id recommend take the earlier one and have a short walk in Lugano. its beautiful!