# ==> $keyptr, @inputs as in your code

 my $rg = join'|', map quotemeta, keys %$Keyptr;
 my @hits;
 push @hits, { /($rg):(.+?)(?=(?:$rg)|$)/g } for @inputs ;

 # thats it

##</code><code>##

 ...
 for my $rec (@hits) {
    print "====\n";
    print "$_ => $rec->{$_}\n" for sort keys %$rec
 }
 ...

##</code><code>##

 ====
 ANALYSIS =>  yada ^M yada 
 CONCLUSION =>  drone drone ^M 
 PREFACE =>  mumble ^M 
 REMARKS =>  ixnay
 ====
 ANALYSIS =>  Chuckle 
 DEFERRED =>  blahblah ^M blah ^M 
 NAME / NUMBER =>  John 369
 REMARKS =>  Yada2