Ask around the internet to see if there's someone willing to say the lines in a voice chat not so you can record it, but so you can hear the proper pronunciation, syllabic emphasis and flow. That can help you tone down your natural accent.
There will probably be people willing to help tweak your dialogue to come out a little bit more natural. A large problem with translations is that they end up being a little too formal because dialects/idioms/etc. aren't generally taught in schools. (How do you do? vs. Hey! or What's Up?)
There are some chats and the like around that are specifically for learning/practicing languages, so even if you can't find a friend to help you out, you can probably a native speaker to give it ago if you're willing to help them out with your language.
Beware of Ninja
- Cosplay and Prop Commissions. Home of my custom parasols.