Mark, it's not clear to me whether you understood my comment. The reason your one-liner works and your roseEncode method doesn't is that your rose2 structure contains no strings. Your one-liner is applied to Symbols, and rose2 does contain some matching Symbols. Your roseEncode function is applied to a String, and rose2 contains no Strings (no Characters), so it reports Missing. In other words, both your one-liner and your function are working.

To simplify your function, let's start with your hard-coded one-liner (slightly simplified for clarity):

FirstPosition[rose2, #] & /@ {s, t, a, r, t}

The algorithm is clear, we just need to replace the specific, hard-coded values with variables. Basically, you're trying to create a FirstPosition function that works with a list of patterns (FirstPosition would look for an actual list if you passed it a list as a pattern). Let's name it FirstPositions.

FirstPositions[structure_, patterns_List] := FirstPosition[structure, #] & /@ patterns

By calling out _List this way, I can create an alternate version that works with a string.

FirstPositions[structure_, patterns_String] := FirstPositions[structure, Characters[patterns]]

We can check how FirstPositions works:

In[8]:= FirstPositions[rose2, {s, t, a, r, t}]
Out[8]= {{6, 3}, {6, 2}, {4, 3}, {6, 4}, {6, 2}}

In[9]:= FirstPositions[rose2, "start"]
Out[9]= {Missing["NotFound"], Missing["NotFound"], 
 Missing["NotFound"], Missing["NotFound"], Missing["NotFound"]}

In[10]:= FirstPositions[Map[ToString, rose2, {-1}], "start"]
Out[10]= {{6, 3}, {6, 2}, {4, 3}, {6, 4}, {6, 2}}

From here, you can add the checking you want (ignoring spaces, normalizing to lowercase, etc).

Rose2 is a definition, a 2 dim array of scrambled alpha-numerics. The roseEn takes a string, throws away spaces etc and passes the results to map. It is called in the print statement and passed the string "start". If cLst is printed out during the function it is {s,t,a,r,t} the same as is passed into the one liner. I will look into the assignment differences, I've tried = before and kept getting errors so rather than fighting with it all the time. Mark