[#4800] Cb conditional issue

Ok, that looks like a bug with CB Conditional not conditioning delimiter fields properly. Will investigate further when upgrading CB Conditional.

Is it possible somehow use the operator "between" in CB Conditional?

Condition for a range of values? No, it has no operator for that. It would only work for integer based values. I recommend using regex and just matching OR cases. Example as follows.

/^(52|53|54|55|56|57)$/

I noticed that in the settings of a field delimiter at the "Available users list?" the value of defaul is "No" (see attached screenshot), is not present the dropdown as for the other fields. Is it possible be this to determine the malfunction with CB Conditional? Can I fix it somehow?

I think that maybe just a translation error. That parameter enables/disables a fields searchability. It's not possible to search a delimiter field value as it's not stored anywhere, but calculated. No it's not the cause of your issue.

I tried it also with a field type "Gravatar", is behaves at the same way as the "Delimiter" (in the profile is hidden in the user list no). At this point are not hidden all those fields that are not directly connected to a user, but which are fields independent.
Now I think the only alternative is to do load a value at the user with CB Auto Action in the registration phase so as to be able then to hide also in the user list. Do you think is a good solution or do you have any idea? If possible I would like to use an image.
Thanks.