How good is ChatGPT3.5 / GPT4 translations?!

I am experiencing mixed results. I want to translate from Spanish into Interlingua, and often found that it ends up translating into Latin, or Italian, instead. This occurs particularly if the Spanish text has Roman numerals. Interlingua is an artificial language with roots in Latin, Italian, and Spanish.
Often I need to redo the work, and translate from Spanish into English first, and then from English into Interlingua.

We have translation services, and tested it with human translators.

We get 95% accuracy. It is great for business purposes. We can do localization across common languages faster and cheaper.

Did you use any specific prompt or just “translate this”?
Because in my case, Chat ignores context sometimes and starts translating word-to-word.