if the ajax-inline editing would work also with conditional fields, then everybody could edit his fields in the profile view without using the profile edit view.

Conditions work while editing a field in profile view if you edit them at the same time using the Additional Fields feature. What it won't do is refresh the profile view of those Additional Fields if they're also displayed individually on the page. Why it won't do that I've already explained above.

In the profile edit view (with Community Builder Profile Pro) only the login data could be edit. By this you can seperate editing "normal" data and login data.

Then I recommend you use CB Profile Pro if it fulfills your needs.

At the moment there is no possibility to have different data sets in profile edit view, so that would be a solution.

Use CB Conditional to show/hide fields as needed. You can even do this based off a value in a URL. Example as follows.

Field: Custom > Value
Custom Value: [get_display]
Operator: Equal To
Value: account

You'd then supply &display=account in your profile edit URL for that field/tab to show/hide. Additionally you just said CB Profile Pro can do this so you could just use that.

I try to establish with RSForms the editing of normal data and in profiler edit view editing only login data. But this is an enormous task.

Putting users data that is editable in multiple locations is bad UX. Users should not and will not navigate all over the place to edit their profile data. It being in one central location is a huge benefit to the user.

Here I have another position: if you have stored login passwords in browsers, the browser will fill in the password in one password field. But in the edit view 2 password fields are shown to change the password. By this you have to delete the automatically filled in password or add it in the second password field. Otherwise you get an error message at saving. And because the login data are hidden under a special tab, you have to search for this. That is not nice.

Decent browsers will not do that (Chrome and FireFox both work fine in my tests). Terrible browser extensions will (e.g. LastPass). We set autocomplete="off" on the password input and on the HTML form it self, which decent browsers and browser extensions will respect. LastPass is a huge offender of this as by default it ignores autocomplete="off". It's not a common problem however.

So I prefer to have 2 seperated data edits: 1) all data and 2) login data. And this is managed at the most online portals I know in this seperated way.

PS: may be it has to do with my usage of CB, I will use it for a real estate portal and have many property data and therefore I need the login data seperated

Then you've 2 solutions. Use CB Profile Pro or and/or use CB Conditional so you can alter profile edit via a URL. Either should work fine. There is no solution for your ajax edit problem at this time. Maybe when full tab ajax editing is implemented it'll fit your needs, but beyond that I've nothing further I can suggest.

CB Conditional will reset a fields value if the condition isn't met. For your usecase you need to turn that functionality off within CB Conditional > Parameters. Currently this can only be turned off globally and not on a per conditional usage (planned to support per conditional usage in a future release).