If you are a buyer of translations, and want those translations to be the best fit for your purposes, there is one thing in particular that you should be aware of: Translations aren’t a one-way street. The better you communicate your needs and expectations, the better you will be served.
In my workshops (and elsewhere) I always insist on the importance of client communication. Meaning: As a linguist – hence, a service provider – you need to be clear and specific in your communication with (prospective) clients.
A transcreator needs deep expertise in translation and deep expertise in strategic copywriting. Expertise in both of these fields is indispensable.
Labeling something a marketing translation when you mean transcreation can be highly misleading.