Are you going for a SE commercial or ME? The 5 hours SE instrument time you reference is in 61.129(a) which lists the experience requirements for a SE rating. 61.129(b) lists the requirements for a ME rating which include 5 hours instrument training in a ME airplane. The other 5 hours could be in an airship as far the FAA is concerned.
If you have the time you can go straight to the ATP as the holder of an ICAO commercial license. The ATP CTP course has its own syllabus for the simulator training. While some of the maneuvers overlap the checkride maneuvers, most of the training is different from what is required for the checkride. You could contact the training center and see how much they can count.
Even if you’re not going for an ATP level type you could complete the CTP as it does not expire. Just be sure to keep the course completion certificate as a record for when you do get ready for the ATP MEL checkride. And if you do a type ride as your commercial checkride the type will upgrade to an ATP type when you get your ATP MEL since the checkride is conducted to ATP no matter what level of certificate you are applying for.