Well you've already done the most important things, which is fit the new belts and check all the bearings. Next is to use the correct torque on the tensioner quadrant bolts. I know the torque in my head but I won't put anything in print without checking the book. I personally never use thread lock on those and I'm not alone.
The belt tension is over thought all to often by many I think and the frequency method is often revealed to be confusing, I've never bothered with it.. It's for musical instruments not motorbikes!!
Sounds like you've got the horizontal tension cock on to me. Even when it's right with a 5mm Allen key you can still get a 6mm through with enough will, so I would be happy with that. Over tight is a bad thing, slightly slack won't do any harm. As you say it won't slip.
Remember to use a 6mm key on the vertical belt with a 7mm being very hard to pass.
It's not a bad idea to just run it up with covers off first time and keep an eye on the tracking of the belts over the pullies.. It's fun watching the white patches of paint shooting round anyway..
