Nothing has changed on Taiwanese side. Renunciation exception does apply to anyone who meets the conditions.
The only additional policy is that Germans do not have to provide renunciation rejections (like I was initially asked to). Mostly because Taiwan’s representative office in Germany has no access to federal government seals and signature examples, due to lack of official recognition. Hence they can not legalize the renunciation rejections. To avoid this diplomatic deadlock they waive the requirement proactively since they know renunciations are not possible anyway.
Renunciation has an official document in Germany. Rejection of the application to renounce is just ‘a formless letter’ from government with a seal and signature saying the conditions are not met.