There have been cases where the conversion is protected between the language specific characters and English characters. Remember you need to look at jurisdiction and what people in that jurisdiction will remember etc.
In Australia the test of deceptive similarity is one of a person being caused to wonder if one product originates from the other trader (having in mind the trademark). Clearly when conversions occur - that confusion can occur.
We had a major case about a foreign word (an Italian word) that went to the High Court (our highest court). Basically it came down to the number of people in Australia that would recognise that word as having its meaning. The other issue with the case was that when translated the word was descriptive (it indicated quality) - descriptive words like that aren't trademarkable in Australia as other traders should be able to use them. So that is why they looked at the population to see how many would know the true meaning.
And I just read that Disney owns the TM for Hakuna Matata - meaning no worries- think Lion King.