Why did you decide to come into US tax compliance? Provided that you are a dual citizen, it's generally a bad idea unless you are planning a move to the US in the near future.

Assume the worst case, that penalties were assessed. If you have no US assets, the IRS would have no means of collecting from you. However, the IRS can ask to have your US passport revoked for an outstanding debt over $51,000. Future travel might be a bit awkward if that happens, and if you don't have a second passport, trouble awaits at the Ausländerbehörde. Do you have German (or other EU) citizenship?

I can't speak to whether any such fines would be imposed, particularly given that you've used the streamlined program. There have indeed been problems with 3520 forms in the past. There have also been fines wrongfully imposed and then reversed, after much correspondence. I wouldn't take it as a given that you're on the hook for $70,000. Wait and see what happens. The CPA sounds like an absolute Vollidiot, by the way.

What you're up against with the pension and ETF is a common situation for Accidental Americans. They save and invest in fully normal ways, particularly using tax-advantaged savings programs in their home country. Then they get scared into US tax compliance, discover that US tax rules treat "foreign" investments like radioactive waste, and get screwed. Far better to stay completely out of the US tax system. The only ones getting hurt are those who file, but fortunately their numbers remain small.