Finding Indic Vowel

How do I search for a vowel in an Indic script?

I want to find and replace all instances of Tai Tham vowel sign UE by vowel sign UUE. The first instance I should find has a tone mark associated with the same base consonant. The shortest string I can successfully search for is base consonant + vowel + tone mark (3 characters). It could be worse, the default legacy and extended grapheme clusters containing the vowel further contain U+1A60 TAI THAM SIGN SAKOT, but I do not need to specify this for the search to succeed. With about 43 consonants and two tone marks in the script, I do not want to manually repeat this search for 2 or 3 characters 129 times.

I had not noticed this problem in Version 3, and indeed the search works in OpenOffice 3.4.1. How do I make the change using LibreOffice Writer?

This problem also affects Thai, and also affects Thai in OpenOffice 3.4.1, so it appears that ‘improved’ support for Tai Tham has impaired functionality.

There is a solution. If one chooses the ‘regular expressions’ option for search in the ‘find & replace’ menu, it will ignore grapheme cluster settings (hardwired?) and find the search string regardless. Find and replace will also work. The setting for find and replace will also apply for the short cut search in the document window.