Ahsan Allahu Ilaykum Sheikh, As a non Arabic speaker I also want to understand what I memorized from my Hifdh. How can I achieve it ? Do I increase in learning Arabic ? Or do I buy Tafseer as Si´di and memorize the Ayat and the summarized explanation ? How can I achieve this Sheikh ?

The most important thing is the knowledge itself, therefore put a large portion of your focus on learning the knowledge itself. As for Arabic, yes you can start learning Arabic on the side as well in sha'a Allah; bit by bit until you start understanding. Knowing the ayah or hadeeth and the meaning is a beneficial means without a doubt.