Thanks for your response but it's just too confuse for me to make it working (I admit to have no skill at all in apex for now).
Let me illustrate my simple old workflow :
Here is my scene, a simple room :

Now I create some keys in camera, while keeping in camera view, with the use of the good camera handles :

Then, if needed, I activate the motion path to adjust some tangent animation trajectory, here in top view :

And that's it. Simple and straight.
Now In solaris :
I create my camera keys in camera view, like in sop. ok it's done.
But, if afterall I make decision that here I need motion path adjustment, I need to redo all my keys in apex ?
Also, with apex I see camera icon at one place but in camera view I'm at another place (cf. scene file) :

I also don't manage to display tangent :

All in all why it's so complicated and we still don't have same features than in sop ?
Can you give me some brightness on this points ?
Thank you