Learn Farsi: شاید حرکات پیوسته یک جلوه‌ی جدیدی خلق کنند. - Perhaps the continuous movements create a new effect.

While non-human plurals typically take singular verbs, using a plural verb is grammatically correct and often done to emphasize the individuality of the actions or elevate the literary tone. Here, the movements are almost acting as active, independent agents creating an effect.

Why do we have both yek and the indefinite suffix -i on yek jelve-ye jadidi?

In Farsi, it is very common to frame an indefinite noun phrase with both yek at the beginning and the indefinite suffix -i at the very end of the phrase. So yek jelve-ye jadidi simply means a new effect. You could also just say yek jelve-ye jadid or jelve-ye jadidi, but using both together is perfectly natural and common.

Why is the verb khalq konand in the subjunctive mood here?

The sentence starts with shâyad, which means perhaps or maybe. Words expressing doubt or probability require the following verb to be in the subjunctive mood. Because khalq kardan is a compound verb, you form the subjunctive by conjugating the auxiliary part, giving us khalq konand.

Does the word peyvasteh (continuous) have any connection to the preposition dar pey-e (in pursuit of) from this lesson?

Yes, they share the same root! The word pey originally means footstep or track, which is why dar pey-e means following or in pursuit of. Peyvasteh comes from the verb peyvastan meaning to join or connect. This shares the root concept of following closely or linking one thing to the next, which is how it gets the meaning of continuous.