Hiya,
Maybe you've figured them out by now, and no doubt you're much better in Filipino than you were 3 and half years ago, but I'll still answer for anyone who comes across this and has the same question in the future (this post has 4.5k views as of the time of writing).
Your answers lie in the Talaan ng mga Daglat (List of Abbreviations) page of the UP Diksiyonaryong Filipino that diksiyonaryo.ph is based on. If you don't have a physical copy, here's an online one:
archive.org/details/ updiksiyonaryong0000 unse/page/n20/mode/1 up?view=theater
The Talaan ng mga Daglat is on page xviii. To view that page along with the rest of the pages, you need an account so that you can borrow the book. It's a weird system for something online, but that's how it is.
You correctly listed the expansions for your first set of abbreviations that are related to grammar. Here are the expansions for the missing:
pnt: pangatnig (conjunction)
pnk: pang-angkop (ligature; linker)
ptk: pantukoy (article)
(Take note, TDC lists 'pnt' as an alternate spelling of 'pantukoy' ang 'ptg' as an alternate spelling of 'pangatnig.')
Your intuition is on the right path for the second list, but it's important to know that these are languages and not dialects:
[ST]: Sinaunang Tagalog (Proto-Pilipino?)
[Kap]: Kapampangan
[Ilk]: Iloko (Ilocano)
[Seb]: Sebwano (Cebuano)
[Iva]: Ivatan
There are many other abbreviations, a full page's worth, e.g. [Hil] for 'Hiligaynon' and
Kol for 'kolokyal.' I saw
Sin here (https://diksiyonaryo.ph/search/barok), but it's not listed in the Talaan ng mga Daglat (maybe it's in the 2nd or 3rd edition of the UP Diksiyonaryong Filipino); I think it means 'Sining' (Art), but I'm not sure. You'll have to refer to the Talaan ng mga Daglat for the expansions of the rest of the abbreviations that you'll encounter.
Lastly, if you can, read the section titled "Gabay sa Paggamit ng UP Diksiyonaryong Filipino" (starts on page xi). It provides useful information for understanding the information given to you for any entry, even in diksiyonaryo.ph
@primesgenato If you see this after 3 and a half years, kamusta? 🤣