To be fair, much of the gap with accents, is to do with exposure, in reality the majority of your media consumption in English is American English not West Midlands English.

Unfortunately the majority of native English speakers (not just from the UK) fail to realise that there is an 'international' business English which has significant differences from how they would speak 'back home'.

From the faux pas I've seen in international teams, my shortlist for the English native speakers:

1. Try to speak slowly and with diction

2. Avoid idiomatic expressions

3. Avoid phrasal verbs

4. Avoid Sarcasm (!)

Do that and 90% of miscommunication in an international setting is gone.