Learn Turkish: Gerginlik yüzünden dosyalarla çıldırırcasına uğraştığını gördüm. - I saw that he was dealing with the files as if going crazy because of the tension.

This uses the lesson's target suffix, -casına (meaning as if or as though). It attaches to the aorist (simple present) tense base of the verb. So, we take çıldırmak (to go crazy), find the aorist base çıldırır (goes crazy), and add -casına to get a word meaning as if going crazy or like a madman.

Does the suffix -casına in çıldırırcasına mean he actually went crazy?

No, the suffix -casına is used for exaggeration or similes to describe the extreme manner of an action. It means he was working on the files with such frantic energy that it looked as if he were going crazy, not that he actually lost his mind.

Could you break down the suffixes on uğraştığını?

The main verb is gördüm (I saw). To say I saw that he was dealing, Turkish uses the object participle -dık. It breaks down as uğraş (deal with) + -tık (participle) + -ı (his) + -n- (buffer) + -ı (accusative case). The final -ı marks the whole phrase as the direct object of what was seen.

Why is yüzünden used here for because of rather than için?