It has been said that all phenomena are conditioned, not intrinsically real
When you asked that, you were quoting an answer of Yeshe Tenley's.
I think the Pali doesn't say "all phenomena are conditioned", but it does talk about "conditioned phenomena" (sankhara) ... and refers to Nibbana as "the Unconditioned" (and other epiphets) ...
see also What are conditioned as opposed to unconditioned phenomena?
I think that the doctrine which Yeshe Tenley was explaining says that Nibbana too is "not intrinsically real". There's an example of that in this answer and its comments; and maybe this comment is a reference to detailed explanations:
You said, "I don't know how to reconcile that with the doctrine that "nibanna isn't conditioned" (or "is unconditioned")." I'd suggest that a careful study of Chapter 25 of Nagarjuna's Fundamental Treatise of the Middle Way along with the excellent commentary by Je Tsongkhapa in Ocean of Reasoning might help to understand this.
So what is intrinsically real?
I don't know how other people understand the term "intrinsically real".
I think (in classic English) that the word "real" meant "thing-like": maybe substantial or tangible. An opposite of "real" might be "ideal", i.e. an idea as opposed to a thing.
According to that classification, the body might be "real" but a feeling might not be (a feeling is more "ideal", i.e. idea-like rather than thing-like). I wouldn't necessarily mean that a feeling is imaginary or non-existent, but it's not substantial nor exactly tangible.
Related to that is the idea of reifying ideas, i.e. the process of treating ideas as if they were real. As you can see from that Wikipedia link (which isn't even Buddhism-specific) that's a complex topic or a set of related topics: different topics include "linguistics" (talking about ideas as if they're real), psychology (perceiving ideas as if they're real), and as a type of fallacy (a type of logical mistake, e.g. mistaking an idea for reality when it's really only an idea, and maybe not even a 'true' one).
I say this to illustrate that the English language or meaning (of the word "real") is complicated, and if you assume you know what it means that might be misleading.
I might add that that emphasis on what's "real", in the sense I described it, might be missing the whole point, from a Buddhist point of view: because Buddhists might dismiss that as mere "materialism".
I'm not sure what "intrinsically" means, either. I think it's used to argue that all composite things, at least, aren't intrinsically real in the sense that, for example, "a chair isn't intrinsically a chair: because if you disassemble it, take it apart, then it isn't a chair anymore".
And I'm not sure what "relative" means. I assume it means that a property exists as a result of comparing one thing relative to another: for example a mountain is high because a valley is low, or shadow is cold because sunshine is warm, and so on -- which I think is central to the Taoist doctrine of Yin and Yang. I'm not sure (I doubt) whether that (relativism) is so prevalent in the Pali. The Pali is very dualistic, IMO, e.g. it consists of doctrine about whether an action is "skilful" versus "not skilful" ... I'm pretty sure it wouldn't say that these aren't real just because they're relative. Another meaning of "relative" I guess might be that it's an artefact of a relationship with the observer: e.g. what I perceive as a "tree" isn't real, that's just an artefact of contact between the tree-as-sense-object with the sense-organs (e.g. the eye), and memories and linguistic associations ("that collection of sense-impressions may be called 'a tree'"), and changes (or vanishes) e.g. when the observer moves.
There's a Pali sutta called the Tatha Sutta ("Real": SN 56.20):
Tatha Sutta: Real
Monks, these four things are real, not unreal, not otherwise. Which four?
"'This is stress,' is real, not unreal, not otherwise. 'This is the origination of stress,' is real, not unreal, not otherwise. 'This is the cessation of stress,' is real, not unreal, not otherwise. 'This is the path of practice leading to the cessation of stress,' is real, not unreal, not otherwise.
"These are the four things that are real, not unreal, not otherwise.
"Therefore your duty is the contemplation, 'This is stress... This is the origination of stress... This is the cessation of stress... This is the path of practice leading to the cessation of stress.'"
The Pali word that's translated as "real" is tatha. Tatha is used in the word tathagatta and also (as well as "real") means "true" ... or "so" (in the phrase, "that is so") or "such".
Anyway that illustrates another meaning of "real": i.e. it means "true". Even in (non-Buddhist) English, something (especially a story) that's "fabricated" implies it might be untrue, or at least (if it's a consumer product) unreliable, disposable, transient.