I recreated what you have mentioned in the instructions and this is what I got as a result. However, I am not sure why you would use year in a list format (I am presuming that it might be for some purpose). Anyway, here is the actual way that I have done and maybe you can check with yours.
The formula should be 'Module 1'.'LIA1'[LOOKUP: 'LIB1'] + 'LIB2'
I have a workaround for that and looking at the instructions you have mentioned, I have presumed that you are not using time as a dimension. Instead, you have used it in a list and later using the same again in module 'A' and as list formatted in (Module B).
Now, there are certain steps that you have to do in order to achieve this workaround.
1) Create a sequence for the years in the list (as a property). Sequence should be 2018 = 1, 2019 = 2 etc...
2) Now create three new line items in MODULE B (LIB2A, LIB2B, LIB2C).
3)LIB2A = LIST Y.Sequence[LOOKUP: 'LIB1'] + 'LIB2'
4) LIB2B = IF 'LIB2A' = LIST Y.Sequence THEN ITEM(LIST Y) ELSE BLANK
5) LIB2C = LIB2B
If you were to use TIME as dimension then you can achieve this by using various functions mentioned in ANAPEDIA like OFFSET, LEAD etc. Since yours is list formatted, this is the workaround that I could think of.
I have attached the snapshots for your reference. If this helps and solves your question then please mark this as the solution.