Goobawambaplex {10,goobawamba (1) 2} & 10
This number is a goobol(Not to be confused with gobbol and gobol) array of tens, a number of order type ψ(ΩΩ^w) (also known as the small Veblen ordinal, or SVO for short). It's about as far as I myself currently have figured out how to easily define BEAF with the array of operator. I'm not exactly sure how to go further, because (for example) setting {X,2X(1)2} = {{X,X(1)2},X(1)2} just doesn't work.
Why is that? The whole reason I chose, for example, X^^2X = (X^^X)^^X is because n^^2n (where n is a number) APPROXIMATES (n^^n)^^n - the same holds true, for example, when comparing n{{1}}2n vs (n{{1}}n){{1}}n. However, {{n,n(1)2},n(1)2} is NOT EVEN CLOSE to {n,2n(1)2} - this shows that defining the structures is now much harder at this point.
Fortunately, Hyp cos of Googology Wiki has an "analysis" of BEAF in terms of the FGH, which gives informal proposals on how big BEAF numbers "should" be in terms of the FGH. What he does is not only a full coverage of BEAF, but it's also helpful for determining how to work with BEAF past {X,X(1)2} & a. The methods for getting to things like {X,X,2(1)2} & a are kind of confusing, but they're reasonably unproblematic.
I'm currently trying to figure out how to work with BEAF past the SVO. But for now, from here on out, in BEAF numbers I will rely on Hyp cos's "analysis" for determing how big they are. I put "analysis" in quotation marks because the analysis isn't very formal (BEAF past dimensional arrays in itself isn't formal), and it's better to describe it as an informal proposal on how big BEAF numbers "should" be and how BEAF "should" be worked with past tetration arrays.
It was {X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X...X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X,X} array of tens with goobol tens