The thing to understand about language learners is that to reach fluency requires a working vocabulary of about 10,000 words. However native speakers have a working vocabulary of 30,000 to 40,000 words. Idiomatic expressions are a whole other problem.
So when addressing non-native speakers it is important to consider word choice and idiomatic expression. You can see this principle even between UK English and US English. When a UK native uses words like nappies, or jumper or an expression like “donkey’s years,” it takes some learning on our part to understand meaning.
Recently when traveling in Germany I found my 2 years of B Average College German enabled me to comprehend about 30-40% of native speakers as they spoke from a church pulpit or tech conference. However, when a German as a 2nd language learner spoke I understood 90% because their limited vocabulary closer matched mine.
If you have the will you can review your presentation for an hour or so with a 2nd language learner in your context and test whether they understand the vocabulary and idiomatic expression. You can work with them to adjust the word choice and make the idiomatic more clear.