Dear Friend,
Of course and indeed, english have become a language of communication at Global level, yet, the local culture, the language by the people attending the training did take a place for the best communication and understanding. Here, the best related to understanding of english at a higher level.
1) A Trainer must have the knowledge of local language not at the best but, relatively good expression with some words put the training in a good spirit.
2) A Trainer should know cultural festivals and their importance. During, the training these festivals should be praised for the co-operation of humanity, possibly the session provided with the delicious foods on these occasions. These will attract the people more close to the training method and the success is written in grand.
3) Difficult sessions should be catered with local language initially and slowly transformation to the global language heed a good response.
4) Native language is not a priority, yet, for a successful training native language is the way. It is the opening spell.
5) A trainer should have a person to get know the local people in the organisation for betterment of training. And the local people who have succeeded in the life/achievements..for quoting.
best of luck...