If so, is this ever enforced?
Using the German translation "Softwareingenieur" of "software engineer" on your LinkedIn page might easily get you into trouble.
Typically, as far as I know, law enforcement agencies only get active in the punishable act "Missbrauch von Titeln, Berufsbezeichnungen und Abzeichen" [abuse of titles, occupational titles and emblems] if the culprit gets denounced by someone or if there is a public interest, but everybody knows how easy it is to make enemies in your job or on the internet.
That being said, in Germany there is no official degree named Diplom-Ingenieur Softwareentwicklung, it is always Diplom-Informatiker. Also, the Expression “Softwareingenieur” is not used, the straightforward translation of software engineer would be either Informatiker (emphasizing the degree) or Softwareentwickler (emphasizing the skill).
This is no legal advice: As far as I know, the regulation is strictly about German titles, so putting “software engineer” in your LinkedIn CV is out of scope of this law.
The reason why I avoided this term is that in Germany, there exists a quite strict of whatx an engineer (Ingenieur) is, which is defined in the laws of many federal states (Ingenieurgesetz [engineering law]). "Ingenieur" (engineer) is a protected professional title:
> https://de.wikipedia.org/w/index.php?title=Ingenieur&oldid=2... (*)
Falsely claiming that you are an Ingenieur when you aren't (by the definition in the Ingenieurgesetz) is a punishable crime in Germany:
> https://de.wikipedia.org/w/index.php?title=Missbrauch_von_Ti...
There exist some boundary cases under which as a software developer you can call yourself an "Ingenieur", but you have to be insanely careful about whether you actually satisfy the legal criteria (see (*)) - in most cases you don't and you are thus a criminal if you do.