Translation:There is sugar in my tea.
My translation: "My tea contains sugar" Your translation: "My tea has sugar." If I'm not mistaken, 'contains' is a synonym for 'has'.
Am I wrong in thinking this should be more along the lines of, "my tea is sweet."?
'There is sugar in my tea' sounds very unnatural, like the sugar is there by accident, along the lines of 'There is a fly in my soup ' (a contaminant I did not put there and certainly don't want). I would normally say 'I have sugar in my tea' or even 'I take sugar with my tea' to express this in English.