Inconsistency on tables

[gabrielcalegari]

I'm using GHTorrent on Google BigQuery (https://bigquery.cloud.google.com/table/ghtorrent-bq:ght_2017_04_01.project_languages?pli=1)

I've found a inconsistency between tables. I've queried the top projects of a specific language with more commits. For this, I've used the table project_languages. But when I queried over the table projects, the column "language" shows sometimes another language. Example: I've queried the top projects ordered by number of commits of projects of Java. When I query in the table projects with the project_id of the another query, the column "language" shows another language like C.

Now, I'm lost. Which field is more fiable? Likewise, there are a lot of commits from 1994. Is it real?