The IC at the bottom of the first page I can see a line on, I don't know about the CB.
Whilst I would think the chances of pregnancy if using condoms correctly is pretty slim, there is still a failure rate so it isn't completely unheard of, although I would imagine it would be things like during manufacture there may be the tiniest of tears or something you can't see, which is unlikely, but then that's why there's only a 3% chance of them failing when used correctly.
The problem with ICs is they can have so many knocks and dents in them, and if say you tried to wipe dust off it or something and your nail catches it, it will mark it so easily! I think there has to be colour to them to be considered positive, I have had grey lines on them before and haven't been pregnant.
I would say usually those CB+ seem to be pretty accurate, I haven't had a false positive before on those.
Going back to the ICs, I would think if they are positive, they seem to be more likely to show a line later on rather than super early when you look at the many reviews on them online. Most seem to have a positive CB or FRER before they see a positive IC, some won't see even a hint of a line until they are due af! The amount of people seeing a positive using those early on seems to be small. It isn't obsolete, however.
If you are seeing a proper positive line on those ICs then they will progress (unless of course you picked up a chemical pregnancy). I think the CB+ is meant to be 25miu? So in theory, less sensitive than the ICs you are using.
Does your OH know you are testing?