Yes, but there is also “When your enemy falls, do not rejoice,”
and also “My handiwork is drowning in the sea, and you are singing?”

It seems to me that one may rejoice only over the good outcome, but not over the death itself.

From the verses you can derive whatever you want. I cited “When the wicked perish, there is jubilation” as an expression, not as a binding source. Common sense says that the death of wicked people is good for them and for the world, and that is definitely something to rejoice over. If you want homiletics on all the verses, those can be produced too, but it’s unnecessary.

In addition, it should be noted that both verses (“When your enemy falls” and “When the wicked perish”) are from the book of Proverbs, so one must discuss separately to what extent they have binding halakhic force as a source from the Writings, rather than simply being good advice with practical wisdom stemming from divine inspiration. And all this even before taking into account that it is not customary to issue a practical halakhic ruling from a verse in a simplistic way; rather, it generally has to pass through the interpretive and halakhic tools of exposition and inference in order to derive Jewish law from it.

As for the midrash about “My handiwork is drowning in the sea” — that was said to the angels (and as is well known, the Torah was not given to the ministering angels…😉), and it is quite clear that the fact that the children of Israel sang and rejoiced was good, proper, and required (indeed, King Hezekiah was sharply criticized for not singing praise).
And in any case, it seems that the midrash comes to present a certain complexity regarding the death of the wicked from the divine perspective, in the spirit of the prophet’s words: “Do I at all desire the death of the wicked, says the Lord God? Is it not rather that he should turn from his ways and live?” (Ezekiel 18:23). And perhaps this too was Hezekiah’s mistake, as told in the famous midrash about the conversation between him and Isaiah when he became ill and was at the point of death: he took heavenly considerations as the measure for how to relate to and act within reality, which was mistaken both in not singing praise and in neglecting the commandment of procreation.

That’s not the point. The point is whether it is fitting to rejoice when there are hostages and people displaced from their homes and the situation is in very bad shape.

Emotion does not have to be dichotomous or static. One can be distressed over the general situation, which has already been going on for a year, and nevertheless rejoice when there is good reason to in light of changing events.
It doesn’t seem to me that shutting down every possibility of joy in the midst of the sea of problems and challenges facing the nation advances anything or helps. On the contrary, the very ability to note and celebrate successes and victories that occur along the way gives strength to keep coping with the troubles.

In the spirit of the poet’s words —
To the beauteous land… whose sorrow and whose joy
are warp and woof in the fabric of its day.