Having downloaded it and looked closely at it, it contains nothing out of the ordinary for a renpy game. The usual .rpy scripting files, a lot of .webp images, and a single audio file that implies a cute girl will be singing a song in this update.It is not made by the developer and bears a distinct possibility of causing a number of problems, some of which could ruin saves.
And having applied the update, it seems to be working just fine. Three of the main girls get four new events each, a side girl gets two new events, and poor, poor Chinami gets no events. Let's all shed a tear for Chinami.
If you have any worries, simply back up your save files before applying the update. Players should be doing that on a regular basis, anyway. Better safe than sorry.