Is there poetry in Pali, and where can I read it, in translation and in original? If so, who are the most important Pali poets, and is anyone still writing in it?
If you googled for Pali poetry, the first result is this page. There are at least 35 Pali poems on that page.
Here you will find many poems that I have translated from the Pali over the years. .....
These poems all come from various parts of the Pali Canon: Theragatha, Therigatha, Dhammapada, Udana, Itivuttaka, Samyutta Nikaya, etc. They are listed here from the newest to oldest, and I will add new translations from time to time to the top of the list.
With details found in this answer, you will find that the original meaning of the word "pāli" itself is "canon", originating from the commentaries upon the Pali Canon. People from centuries ago couldn't even remember the original name of this dialect or language, so they mistakenly called it "Pāli", thinking the term "pāli-bhāsā" (which actually means language of the canon) actually referred to a name - Pali language. The term "bhāsā" means language. By the way, there is no upper case or lower case in Pali.
So you will find that Pali is used only in the Pali Canon, commentaries upon the canon and also later writings related to the canon like the Visuddhimagga. So, it's very unlikely that you will find non-Buddhist poems in Pali. Pali is not a common literary language unlike Classical Sanskrit.