A modest attempt:
Lyrical/Free-Flowing Translation (for easier comprehension)
You with brahmā’s Skull as Begging Bowl; the Protector of brahmā!
You, the timeless one, who cooks Time himself, who cooks the souls bound by limited agency (and other limiting factors)!
You who protects that which cooks/burns up the the dark mass of sins!
You who perfects the two classes of souls who are no longer bound by limited agency : One which becomes unbound only at the uproarious end of time during dissolution & One which becomes unbound without such time-bound conditions.
Translation with word by word breakdown:
You, the protector (pāla) of brahmadeva (ka) who has the skull of brahmadeva (kakapāla) as his begging bowl (pāla)!
One could interpret this as either: a. That śiva has graced brahmā by that act of removing the fifth head; or b. one who protects brahmā even as he holds the skull of the fifth head. A symbolic meaning of the removal of the 5th head is given by tryambakaśambhu in his kiranāgama-śisuhitavṛtti as the awakening of the kuṭilā-śakti in the heart region, which is seen as the abode of brahmā in the kāmikāgama.
This verse, for convenience, can be rewritten as two distinct parts, with the term, “kāla” duplicated.
You, the timeless one (akāla) who cooks the time (kāla-pāka) itself, who cooks the kala-s (kalapāka), that is the sakala class of jīvātmas, ones covered with kalādi (kalā/कला, etc) bandha-s i.e. limited souls like us!
kala-pāka-kālaḥ—Here, kālaḥ/time is the subject of the sentence; the kāla which “cooks” the souls immersed in bondage due to a sense of limited agency (the sakala-s, the kala-s/कला:, who are bound by kalā).
kāla-pāka-akāla—Here, kāla/time becomes the object, with akāla becoming the subject in the vocative case (sambodhana-vibhakti). You, the timeless śiva, who is the very destroyer of time (I.e. destroys time)!
Please do not confuse kāla/काल (time) with kalā/कला, which is a unique concept in śaiva philosophy (particularly well-developed in the siddhānta flavour of śaivam), which, to put it simply without complicating excessively, refers to the idea of “limited agency” that we all have: “I am a particular individual who is the agent of these actions and the enjoyer/sufferer of their fruits”. Those who keep suffering due to the effect of kalā; they are sakala-s, like us, whom I have referred to here as kala-s. These souls keep getting “cooked” by time in the fires of repeated birth and death.
Do note that the term, “pāka”, occurring in the 2nd, 3rd and 4th lines, is used in different senses.
2nd line: Cooked in the fire of repeated saṃsāra
3rd line: Refers to the cooking/burning off of sins by the purifying śivajñāna (Wisdom of the siddhānta)
4th line: Refers to the cooking (spiritual ripening/perfection/maturation) of two categories of souls, who are above us, the ordinary, sakala category of souls
You, the protector (pālaka) who cooks the bundle (kalāpa) of dark sins (kāla-pāpa). Or alternatively, it could mean the one who protects the śivajñāna (i.e. the siddhānta), which cooks the bundle of dark sins!
The ones who become akala-s only during pralayakāla, which is the uproarious moment of kāla (kāla-kalakala-akala), that is the pralaya-akala-s (pralayākala class of jīvātmas).
Those who are akala-s outside the boundaries of time (akala-akāla); that is, the vijñānākala-s (vijñāna-akala-s); you, the one who causes their mala to ripen, that is, malaparipAka; literally and figuratively, you, the one who cooks both of them to spiritual perfection (pāka)!
Or simply put: You, who “cooks” (i.e. perfects or causes to mature/ripen) the pralayākala and vijñānākala categories of souls!