It sounds like you are looking for an Excel formula rather than some
VBA code (or perhaps looking for either, as long as it does what you
need).

In Excel, one way around the problem is to use formulas in multiple
cells to determine what to do with the entry in $u$3.

Here is how you could use 3 cells to check for up to 13 possible
entries in cell u3.

1. In cell v3, make a nested IF statement checking for just 7 of the
possible values in u3. If none of those seven appear, the formula
will return some other string or number of your choosing, for example
"xxx":

IF($U$3="pe",'G4'!T352, IF($U$3="lo",...etc..,"xxx")))))))
So, if none of those seven terms appear in u3, cell v3 will just
contain "xxx"

2. Then, put another nested IF in the next cell over (cell w3). It
should first check if v3 contains "xxx". If so, then it continues
checking for 6 possible values in u3 using the nested-IF structure.
Otherwise, it returns the string "No match".

So, cell w3 would look like:
=IF(V3="xxx", IF($U$3="wk",...etc..., "No Match")))))))

3. Finally, cell x3 has:
=IF(V3="xxx",W3,V3)

The value in x3 will be either one of the values you are after, or the
words "No match".