The Cyrillic transliterator does not work correctly

Instead of some words, the function returns an empty string, such as "**o'clock**" or "**Straße**". And even writing "**Strasse**" the function returns as "**страссе**" when it should be "**Штрасэ**"; or for example "**quick**" returns as "**кык**" when it should be "**квік**" or "**кўік**".