The question is how it behaves if the rear property is officially separated.
That does not change the planning law.
Does the building depth from the street still apply or does Paragraph 34 then come into effect?
No one here can answer which planning law applies to you, since we neither know the property nor the mentioned plans
Baunutzungsplans in der Fassung vom 28.12.1960
Bebauungsplan XIV-A von 1971
förmlich festgestellten (f. f.) Straßen- und Baufluchtlinien
and regulations
städtebaulichen Vorschriften der Bauordnung für Berlin (Bauordnung Bln) von 1958
Do not know. Also, ’s posts contain question marks to whose clarification you have not contributed.
I have now looked at the aforementioned ordinances, plans etc. and found that these measurements are nowhere fixed in writing.
To what extent regulations from the time before the entry into force of the Building Use Ordinance 1962, especially those issued after the promulgation of the Federal Building Code in June 1960, can or must still be applied today is not so easy to answer even for experienced experts. Your statements suggest that the competent authority for the area in which your property is located has dealt intensively with the topic and has come to the named requirements.
still applies as a transferred (qualified) development plan
Where does this quote come from? Of great importance here is the word in brackets "qualified". Why was it bracketed? If the authority interprets the regulations so that a qualified development plan applies to your property, then indeed no specific eaves heights can be invented. A development plan is qualified if "
it alone or together with other building law regulations contains at least provisions on the type and extent of the building use, the buildable areas of the property and the local traffic areas" (§30, para. 1 Building Code).
I therefore assume that the existing provisions only partially apply to the rear properties and the qualification only refers to the front properties. Then only a simple development plan would apply to your property, which means that the topics for which there are no provisions must be derived from §34.