This seems to work with your sample data (some additional test cases added):

use strict;
use warnings;
use 5.010;

my $pat1 = qr |(\d-\d\w{2}\.\w+)|;  # eg  3-123.7  2-3cd.e
my $pat2 = qr |([A-Z]\d{2}\.\d+)|;  # eg  A12.34   Z56.78

my $title;
while ( <DATA> ) {
  chomp;
  if ( /(.+)(\(.+\))$/  ) {      # Better regex for 'title' lines??
    $title = "$1$2;";
  }
  else {
    next unless /$pat1|$pat2/;
    my @items = grep length, split /$pat1|$pat2/;
    say $title, splice @items, 0, 2 while @items;
  }
  
}

__DATA__
Titel Text (A12-3)
3-123.7 Just another (small) text 3-123.8 Some more text
A12.34 Another item B56.78 Yet another item
Another Titel Text (B23-9)
Some trash here
12-22a **This is trash***
1-22a.b Just another text 
2-3cd.e Some more text
W12.34 Another item 
Z56.78 Yet another item Z56.78 And another!! Z56.7a And another!!!
Some trash

[download]

Update: Cat walked on keyboard as I was posting. Please advise if you detect paw marks.

In reply to Re: Insert newline by Not_a_Number
in thread Insert newline by Anonymous Monk

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