This question is old at this point, but I think the answer is in need of an update.
ngx-translate has been largely abandoned. The author of ngx-translate, ocombe, is hard at work at Google to improve the built in Angular method. He transitioned ngx-translate to maintenance only. As of this date (May 2021), he has not done any maintenance on ngx-translate for 11 months including no update for Angular 11.
ngx-translate no longer appears viable for projects newly internationalizing Angular.