I think you need to be a Senior or above to create a thread in there now. It was implemented a few months ago or so due to all the bounty translation spammers posting their Announcement threads in there (which aren't allowed).
What thread did you want to start exactly?
I wanted to add a Bangla thread to help the Bengali speakers. This will help them to understand the forum. I will give my best to educate them about the cryptocurrency world.
There are few threads already I can see but non of the OP has any good information to provide except few lines of spammy topic.
https://bitcointalk.org/index.php?topic=631891.0 ==> বাংলাদেশ (Bengali)
https://bitcointalk.org/index.php?topic=1979138.0 ==> বাংলা (bangla)
https://bitcointalk.org/index.php?topic=1344309.0 ==> BANGLA
My idea is to create a new topic with basic guideline and update the topic with URLs when new information will be added in the comment section. This way the community will have better understanding about cryptospace and of-course about the BitcoinTalk forum.
I do believe bunches of members who are not good at English language, still wondering about this whole new space.
I'm also from Bangladesh. It will be really good to see Bengali thread. Some people do have less understanding in English.
Sometimes I feel like I should create some posts in Bengali so that people can easily understand about this forum and also about the rules. But I can't because I'm not allowed to create new topic in other language.
Although I can post in the above url(thread) you mentioned but this will not make enough exposure.
I'm totally agree with you. It will help to reduce the spam too.