A pet-peeve of a lot of South Africans, including myself, is when people speak of Africa as if it is one country, or one place separate from the rest of the world. Africa is HUGE. The distance from Tunis on the Mediterranean coast to Cape Town on the Southern Tip is about 8,000 km as the crow flies. That is about the same distance as Amsterdam to Beijing. If you have visited Beijing, you haven't visited Amsterdam. If you have visited Tunis, you haven't visited Cape Town.
The problem is this peeve also works both ways. A friend of mine is working on a project where a lot of business is done in Africa. That is the corporate definition of their area of interest. When he joins conference calls, they will often switch from Arabic to French. Neither of these will be their local language, but they will speak both fluently. My friend speaks neither, so then asks (slightly embarrassed) for them to swap to English. Again, fluently.
Swahili is the widest spoken African language. As Arabic and Persian traders started dealing with Africa a trading language was needed. For the equivalent of my friends business meetings - but a long time ago. It was originally written in Arabic Script. While it is now the first language of about 3-15 million people, it is spoken by about 100 million people.
My friend has started French lessons. Many non-English first language Europeans are adept at picking up new tongues, and training their ears to understand variations. This is like the many skillful linguists in South Africa which has 11 official languages. The 'borders' of these official languages were artificially created as languages were built up as one of the blocks of Nation States.
The reality is that language is as full of flavour as people. People don't stay still and don't fit into categories. To truly see, and hear, people... language needs to go back to the kitchen. Adding to your vocabulary can't stop once you have 'finished' mastering your home tongue. Your tongue needs to move with you.
A (small) start is saying someone's name the way they want to be greeted - rather than giving them a name that doesn't need any effort from you.