First, EXCELLENT POINTS in Discipulus' reply above.

Refresher: OP wants to capture a specific word and some words around it (no definition of why) in any lines of a moderately large text file which contain the specific word -- for some sort of corpus analysis.

Now, for another approach to the regex, we can define $word (to capture the 'nearby words' OP wanted) in terms of alpha-content rather than by character-counting. (As done here, we must insert single spaces between the words in the regex itself but could have including most of them in the definition of $word):

 #!/usr/bin/perl
 use strict;
 use warnings;
 use 5.024;
 
 # 1204380
 
 my $string = 'tryna';
 my $word = qr /[a-z]+/i;         
 #           any word comprised solely of letters a-z, UC or LC, follo
+wed by a space
 my (@slurp, $line, @found, $found);        
 #           declare vars; bad practice to do as globals, but simpler 
+to read
 
 @slurp = <DATA>;     # read each line of __DATA__ into var $slurp;
 for $line(@slurp) {  # read thru array @slurp line by line
 if ( $line =~ /($word\s$word\s$string\s$word\s$word\s)/gix ) { 
 #               Match only if there are two $word instances before $s
+tring and a 
 #               space following the second $word after $string
         push @found, "\tmatch: $1";                         
 #               When Ln 16 matches Ln 17 pushes the match (+ a visual
+ marker) to @found
         print "full original line with a match: $line\n";   
     }
  }
 
 for $found(@found) {
     say $found;
 }
 
 __DATA__
 
 123 abcde this sentence has foo bar tryna much too long for my taste 
+ CONTAINS MATCH
 this doesn't have the magic phrase 123456 7890 abcd3e fc.
 much too long for my taste but tryno tryna foo bar baz   CONTAINS MAT
+CH
 work was put into the tryna document which shows good work CONTAINS M
+ATCH
 problems with our out of town and other tryna that never show up  CON
+TAINS MATCH
 Tryna fill to gully and TRYNA upside of big Pine CONTAINS MATCH TWICE
+ BUT ...
    ...FAILS ON Ln 15 BECUZ THERE IS NO $word NOR ANY SPACE ...
    ...PRECEEDING THE FIRST INSTANCE OF $string!
 no searchstring here
 endit
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And here is the output (the full lines are redundant to OP's stated needs but are included for clarity):

F:\PMonks\>1204380.pl
full original line with a match:  123 abcde this sentence has foo bar 
+tryna much too long for my taste  CONTAINS MATCH

full original line with a match:  much too long for my taste but tryno
+ tryna foo bar baz   CONTAINS MATCH

full original line with a match:  work was put into the tryna document
+ which shows good work CONTAINS MATCH

full original line with a match:  problems with our out of town and ot
+her tryna that never show up  CONTAINS MATCH

full original line with a match:  Tryna fill to gully and TRYNA upside
+ of big Pine CONTAINS MATCH TWICE BUT ...

        match: foo bar tryna much too
        match: but tryno tryna foo bar
        match: into the tryna document which
        match: and other tryna that never
        match: gully and TRYNA upside of

F:\PMonks>
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