Hi Gabriele,
I am a bilingual in Japanese and English, and would be happy to help you with this translation.
See below for my translation:
"In accordance, please be sure to record/punch-in your times on your time card hereafter.
Now, please be advised that, at the time of processing on the 20th of every month, if there are days we are unable to confirm the record of your clock-out time, [your hours] will be processed without calculating those [missing] hours (it will not reflect on your salary even if you came into work).
We ask for everyone's understanding and cooperation."
Let me know if you have any questions.
Paz,
-Daiji