I want to know the answer to the following question:
What would be problematic for a multilingual character set or font to provide?
All the background I'm provided with is that "Without letter case, a "unified European alphabet" – such as ABБCГDΔΕZЄЗFΦGHIИJ…Z, with an appropriate subset for each language – is feasible; but considering letter case, it becomes very clear that these alphabets are rather distinct sets of symbols.". Is that enough to answer the question?
Answer: no