If all the information in the steps (Person; Relation; Reference; Files) is mandatory, and you are worried that there is a high risk of failure to save (timeout / system failure), then it would make more sense to make this a multi-step process, and replace 'Save' with 'Next'.
Of course, you can also auto-save on opening of the next accordion, and achieve the same results. However, the use of the accordion pattern in this type of form is not really standard, and therefore may be confusing. Also the way it is implemented here makes the information look like it is non-mandatory, in my opinion. If it is non-mandatory data, then by all means carry on, as I think it would work quite nicely.
The drawback with a multi-step solution, is that you have to find a way to return to a part-saved form, and that is a whole extra set of use cases which may not be worth it, depending on who your audience is.
My experience of user testing on large-scale public-facing projects is that customers perceive really big forms as off-putting. Well, they say that they do when you interview them. I have never seen any data that proves a large form increases dropout rates, but I can believe it would. So that might be a good argument for adding in the partial-save use cases.
However (and I'm making an assumption here) your form looks like it would be used by a small set of users who would use it multiple times and rapidly gain expertise. Also that they would be adding more than one person per session. If that is correct, I would not bother with the extra complexity. This kind of user would be hampered by the additional steps and time taken, they might appreciate being able to enter / cut and paste information into the form in different order, and probably would not be intimidated by a long form.
If this is the case, my instinct would be to provide one big long form.
Hope this helps