Julia: 16 bytes, score: 8

length([1:2])+V   # where V takes value critical version minus 1

I cannot quite remember which version of julia this changed in (stuff gets deprecated very often), but there was some point in the language where this:

julia> [1:2]
2-element Array{Int64,1}:
 1
 2

became this:

julia> [1:2]
1-element Array{UnitRange{Int64},1}:
 1:2

from one major version to the next. I think it was probably from v3 to 4? (in which case V = 2)

Julia: 21 bytes, score: 10.5

(length([1:2])+V)/10   # where V takes value critical version minus 1

I cannot quite remember which version of julia this changed in (stuff gets deprecated very often), but there was some point in the language where this:

julia> [1:2]
2-element Array{Int64,1}:
 1
 2

became this:

julia> [1:2]
1-element Array{UnitRange{Int64},1}:
 1:2

from one version* to the next. I think it was probably from v0.3 to v0.4? (in which case V = 2)

_{* julia is still in major version 0}