In issue 43768, I've submitted the new Thai locale data th_TH.xml,
which include a lot of new outline styles. The changes have been
included in OOo 2.0.1.
Among the outline sytles, there's two styles similar to the one below.
They are offcial formats in some governmental documents.
(The numbers actually use native numeral)

1.
    1.1
       1.1.1
          (1)
             (1.1)

For the entry, I write the OutlineStyle like this :-

<OutlineStyle>
    <OutLineNumberingLevel Prefix=" " NumType="12" Suffix="."
BulletChar="0020" BulletFontName="" ParentNumbering="0" LeftMargin="0"
SymbolTextDistance="50" FirstLineOffset="0"/>
    <OutLineNumberingLevel Prefix=" " NumType="12" Suffix=" "
BulletChar="0020" BulletFontName="" ParentNumbering="1" LeftMargin="50"
SymbolTextDistance="50" FirstLineOffset="0"/>
    <OutLineNumberingLevel Prefix=" " NumType="12" Suffix=" "
BulletChar="0020" BulletFontName="" ParentNumbering="2" LeftMargin="100"
SymbolTextDistance="50" FirstLineOffset="0"/>
    <OutLineNumberingLevel Prefix="(" NumType="12" Suffix=")"
BulletChar="0020" BulletFontName="" ParentNumbering="0" LeftMargin="150"
SymbolTextDistance="50" FirstLineOffset="0"/>
    <OutLineNumberingLevel Prefix="(" NumType="12" Suffix=")"
BulletChar="0020" BulletFontName="" ParentNumbering="1" LeftMargin="200"
SymbolTextDistance="50" FirstLineOffset="0"/>
</OutlineStyle>

Notice the different ParentNumbering in each level.
However, the actual result is :-

1.
    1.1
       1.1.1
          (1)
             (1.1.1.1.1)

You can try the above outline styles in OOo 2.0.1(RC). 
- Set the locale to Thai
- goto Format->Bullets and Numbering->Outline 
- choose the 12th style
- try add some text in different level to see all outline levels

Using "Options" tab on "Bullets and Numbering" dialog,
I found that at level 5 "Show sublevels" is 5 (at level 4 it is correctly 1).
Reducing the number from 5 to 2 will get the correct result.

I've checked i18npool/<platform>/misc/localedata_th_TH.cxx that corresponding
outlineParentNumbering#[] array contains the correct value {0x31, 0x0}.

I guess there may be a problem somewhere.

Expect result :-
(in native numeral)
1.
    1.1
       1.1.1
          (1)
             (1.1)