Yes we do, at least for the kings and queens in the “first” kingdom, before the fall of Jerusalem in 1187. They were buried in the Chapel of Adam, one of the chapels of the Church of the Holy Sepulchre. The Holy Sepulchre is where Jesus’ tomb is supposed to be, and when the crusaders arrived there were several smaller churches and chapels marking all the important sites of the crucifixion/resurrection. In the 1140s/1150s, the crusaders rebuilt the site and consolidated all the chapels into one larger Gothic cathedral. That’s the structure that still exists in Jerusalem today.

The tombs remained in the Holy Sepulchre, mostly undisturbed. When Saladin recaptured Jerusalem in 1187, he left them alone. When the Khwarizmian Turks pillaged Jerusalem in 1244, they took everything of value they could find in the cathedral, and probably damaged the tombs, but didn’t destroy them entirely. They were still there until 1808, and there are some descriptions and drawings of them from 18th century visitors to Jerusalem. The tomb of Baldwin I, for example, apparently had an inscription that compared him to Judas Maccabeus. Unfortunately in 1808 they were destroyed by a fire in the cathedral, and afterwards the material was reused for other purposes, or eventually found their way into museums.

“Of these tombs, we know for certain only of fragments of the tomb of the child-king Baldwin V, which was in the form of an elaborately carved sarcophagus…A fragment probably originating in one of the tombs, consisting of a group of small, twisted pillars, is now on display in the Museum of the Flagellation in Jerusalem. A group of monuments similar to the sarcophagus of Baldwin V are found in secondary use on the Temple Mount. These may have been the tombs of members of the royal family or other high nobles.” (Boas, pg. 180-81)

The only pre-1187 ruler who was buried elsewhere was Queen Melisende. Her tomb was in the crusader Church of the Tomb of the Virgin Mary, outside the city in the Valley of Josaphat. The other wives of the crusader kings were also buried there, but none of those tombs are there anymore.

After 1187, the kings and queens were buried elsewhere. Guy of Lusignan was buried in the Templar church in Nicosia on Cyprus. His wife Sibylla died of disease during the Siege of Acre on the Third Crusade in 1190, and presumably she was buried in a mass grave with other victims of the siege.

In the thirteenth century the kings and queens were usually not actually present in the kingdom. Queen Isabella II (who did live in Acre, initially) married Holy Roman Emperor Frederick II in Sicily, and then died there and was buried in the cathedral in Andria. Often the rulers of Jerusalem were also kings/queens of the crusader kingdom on Cyprus, and they were buried in the Cathedral of St. Sophia (or Holy Wisdom) in Nicosia. I’m not entirely sure about Cyprus but I don’t think the tombs are still there (it’s now Selimiye Mosque).

Sources:

Josef Strzygowski, “Ruins of Tombs of the Latin Kings on the Haram in Jerusalem,” in Speculum 11 (1936)

Alberto Prodomo, “The Tomb of Queen Melisenda,” in New Discoveries at the Tomb of the Virgin Mary in Gethsemane, ed. Bellarmino Bagatti, Michel Piccirillo, and Alberto Prodomo (Jerusalem, 1975)

Zehava Jacoby, “The Tomb of Baldwin V, King of Jerusalem (1185–1186) and the Workshop of the Temple Area,” in Gesta 18 (1979)

Jaroslav Folda, The Art of the Crusaders in the Holy Land, 1098–1187 (Cambridge University Press, 1995)

Amit Reem, “Burial Customs in the Crusader Kingdom,” in Knights of the Holy Land: The Crusader Kingdom of Jerusalem, ed. Sylvia Rozenberg (Jerusalem, 1999)

Adrian J. Boas, Jerusalem in the Time of the Crusades: Society, Landscape and Art in the Holy City under Frankish Rule (Routledge, 2001)