S. R. Faruqi:

ʿishq hai = praise be to

Here, kaisā kaisā ʿishq means passion 'in what various circumstances' and 'in what various styles/moods'. The expression baham kiyā is very interesting, because in it there's also a suggestion that lovers have carefully searched out and collected many different kinds/styles of passion. As if passion is something like diamonds and pearls, that people search out and amass, and collect with great ardor.

The interpretation of kaisā kaisā can extend not only to the present state of passion, but also to its future. That is, to that passion that wouldn't let them go until it had taken their lives, that passion that would drive them mad, that passion that would cause them to renounce the world, etc.

In this whole ghazal the 'mood' is more of situation/state [ḥāl] than of words/speech [qāl]. There's an ecstasy [tavājud] that I've never seen elsewhere, except in some verses of Maulana-e Rum's 'Masnavi', and in some of his quatrains. The whole ghazal is extremely 'tumult-arousing'.

FWP:

SETS
MOTIFS
NAMES
TERMS == TUMULT-AROUSING

SRF speaks of this whole ghazal as 'tumult-arousing', and sets it in a markedly Sufistic frame. The opening-verse, {1158,1}, is a particularly good case in point

kyā ḥaqīqat kahūñ kih kyā hai ʿishq
ḥaq-shināsoñ ke hāñ ḳhudā hai ʿishq

[how can I tell the truth/reality of what is passion?!
in the view of truth/right knowers, {the Lord is passion / passion is the Lord}]

For more on this idiomatic usage of ʿishq hai , see {307,4}.