The project requires searching text through gigabytes of data, getting the right translation quickly (in milliseconds rather than seconds) in the requested language, displaying it in a responsive UI to help the translator do his/her job.
I have extensive experience using Elasticsearch 2.x & also 5.x for full text search and analytics. I also have 3+ experience in designing big data based data-models on hadoop, hbase, cassandra including 3+ years of experience in processing big data using Apache Spark & mapreduce. I am currently co-authoring a book on Learning Elastic Stack 5.x. With my experience in API design, web/full stack development, I can develop a web site that scales really well on top of Elasticsearch & Hadoop (if required after further discussions).
My approach to solving this problem would be to start with lean architecture as follows. Will follow lean principles add only required technologies and iterate quickly. Following is the high level technology stack -
UI (HTML5 + ReactJS) -----> REST API (Java) -------> Data Storage (Elasticsearch 5.x)
I would be keen to discuss in more depth and listen to the detailed requirements.