What is the ruling on listening to someone who does not perfect Tajweed, whether the listeners are in the same place or through media like radio, phone, YouTube, or audio recordings?

There is no harm in listening to a recitation by someone who is not proficient in Tajweed (definition), and listening is not prohibited merely because the reciter does not master Tajweed. Reciting with Tajweed is recommended as long as the reciter articulates the letters from their correct points of articulation and does not err in the vowelizations (ḥarakāt al-iʿrāb). Anything beyond that, such as ghunnah, madd, and idgham, is recommended but not obligatory.