First of all, the 'first link' I mention in the title is this:
How to tell a participle from an adjective?
and despite being 5 years old (irrelevant), it is the closest I could find to helping with my question.
I know in English, participles/verb forms are used as; adjectives, to create a verb tense (not looking down this rabbit hole), or a passive voice (doesn't seem relevant here), but here it seems just as an adjective (assuming these three uses are the same uses in Russian).
I could not find a suitable adjective for 'allotted', and all attempts led me to (mostly) PPP participles (In English, despite originating(?) from a verb, this seems a legitimate adjective, both attributively and predicatively). This led me to the above link, and the lower one.
It all started with my attempts at translating this English sentence to Russian:
I am sitting at my desk, and while observing my allotted time pass, realize that I do not know a sufficient number of Russian words to describe my day.
and did so, with marginal success to,
Я сижу́ за свои́м столо́м, и (наблюда́я и́ли смотря́)[present imperfective adverbial/gerund], как проходи́ть моё (вы́деленное и́ли отведённое)[past passive perfective participle] вре́мя, понима́ю что не зна́ю доста́точное коли́чество сло́в что́бы опи́сать мой день.
The answers in the link above mention a distinction by either time,
A participle is a form of a verb that describes change over time. An adjective describes a more permanent attribute.
or.... 'manifestation of change',
As far as I know, the participles mean "the ones which are being changed" (your example #1), and the adjectives mean "the ones that can be changed"
though the latter person qualifies this only for the specific examples in that link.
These distinctions do not (seemingly) apply here... 'allotted' definitely won't change over time.
Is there any concern over using a PPP as an adjective if it doesn't fit the above two qualifications? Would there then be no necessary distinction, and thought, over using PPPs if one cannot find a good adjective?
Further looking around to help find the difference brought up this link, use of passive past participle, but problems with the example, as well as lack of distinction between how it was used (https://en.wiktionary.org/wiki/%D0%BE%D1%81%D0%BE%D0%B7%D0%BD%D0%B0%D0%BD%D0%BD%D1%8B%D0%B9 says it is both an adjective and a PPP participle) wasn't enough for me to understand.