Nice of you to offer a complete Sindhi translation of joomla! 1.5, which will be appreciated by the Sindhi speakers
As suggested earlier in this thread we do already have Sindhi sd-PK installation files included in the core distribution, and we do have a Sindhi Translation Team and coordinator, as can be seen at the full list of current Translation Teams:http://community.joomla.org/translations.html
But as you noticed there seems to be some inactivity of that team, and the Sindhi site package is not up-to-date for latest joomla! 1.5.20, and no admin package available.
Therefore we are pleased by your offer to continue this task and possible take over in case the other team has turned fully inactive.
You would need to accept the Translation Policy and then send the new site and admin packages for review to one of the members of the Joomla! Translation Coordination Team:memberlist.php?mode=group&g=47
I would suggest you to send a pm directly to 'ste', and she will then kindly guide you.
PS: For the specific question of having Sindhi be default at installation, then this is a matter of the language detected in the browser you use. If you have Sindhi set, then joomla will present Sindhi, and in case english is set in browser then you could be presented with en-US
Thanks again for offering a volunter translation effort
_________________Ole Bang Ottosen
Kommerciel Support, Migrering og Kurser i joomla 2.5 www.ot2sen.dk
Dansk Joomla! support websted - www.joomla.dk