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Without a reference, I do not know which question to look at. Once a question has a comment, it is considered answered by the system. This will mean that I do not see it under my unanswered questions list. Often I will not even get to see replies. It is best to start a new question, and make sure not to comment on it, or I will not see it.

From you description I suspect that your Cassia tree has a condition known as "alchoholic flux" as a result of the heat and drought stress. See the following article for more information:
https://www.gardeningknowhow.com/plant-problems/disease/alcoholic-flux-in-trees.htm

There are other possibilities, especially if the exudation is associated with a wound or cavity.

Tree trunks don’t absorb water for the purpose of growth.
Water droplets often serve as vehicles to carry bacteria to your tree.
The water that does fall to the ground around the tree is too close and does not benefit the water-absorbing roots closer to the outside of the canopy.
Place or direct sprinklers or irrigation systems to avoid tree trunks.
If you can’t avoid the tree trunk, adjust the spray to spare as much of the tree trunk as possible.
If you want to water your tree, place the sprinkler half way between the trunk and the edge of the canopy and remember tree roots need to be watered longer than any other plant in your yard.

Sorry, not familiar with this term.

It appears to be a colony of multiple fungi. One of which looks harmless, but the other could cause you an issue. This is a simple fix for such a small patch.

When you water, just replace 1/4 of that with peroxide. This will take care of the issue. Reapply after a few days if it comes back. After one or two treatments, it should clear off.

Just make sure to let your soil dry out almost completely before watering again. This will keep infections from starting in the soil. Infections are common, and most are harmless, but in this case you can cure this quite easily.

It would likely survive, but I would be sure to consult all local laws on each end when it comes to bringing back vegetation. Some plants can be blacklisted, or have limitations based on diseases from local and non local soils.