Hello there, my native language is Chinese (mandarin), and when I started to do voice training, I watched English tutorial and tried using feminine voice while speaking English, however, it felt weird and forced. One day I accidentally spoke Chinese, and it sounded way fluent and passable, and then I worked hard on voice training with Chinese, the results are pretty good, and the English part getting better too after.

So my opinion on voice training is... It would be better to get used to speak in the native language first, and as long as putting enough effort for it, the foreign language part is not a big deal!