i create categories with English and Thai language  but link categories with Thai language not work and English work well
 for Thai language link show like this :

mysite.com/blog/-c1
-----
mysite.com/blog/-c4

 a lots of bugs and need to improve...

This is first bug you have reported, 1 can be a lot of as well as to few.
If you want to modify plugin and you do not know how, unfortunately such "bugs" can be fixed just by hiring developer that will do your custom requirements.
Can you send category name in thai? There is function to remove special chars that could remove thai as well.
Is this problem with articles as well?

i got this problem too, why it remove special chars?
i think it should SEO url like
mysite.com/blog/categories/c1 or c2 c3 ...c9.
and article too mysite.com/blog/article/b1 ---b9

does it can ?

also categories and article title that input with special chars  it not found? page not found.

It removes to ensure url works.
Can you give problematic name/title

like @Healthy Home said. it not work for both categories and title when type Thai character , it's not have slug so when click on article it not found

title = แฮ็กแบ็คด้านบนของรถที่เร็วที่สุด
categoies =รถ

Thanks

@dom
No issues found:
https://plugins2.abprofitrade.eu/blog/%E0%B9%81%E0%B8%AE%E0%B9%87%E0%B8%81%E0%B9%81%E0%B8%9A%E0%B9%87%E0%B8%84%E0%B8%94%E0%B9%89%E0%B8%B2%E0%B8%99%E0%B8%9A%E0%B8%99%E0%B8%82%E0%B8%AD%E0%B8%87%E0%B8%A3%E0%B8%96%E0%B8%97%E0%B8%B5%E0%B9%88%E0%B9%80%E0%B8%A3%E0%B9%87%E0%B8%A7%E0%B8%97%E0%B8%B5%E0%B9%88%E0%B8%AA%E0%B8%B8%E0%B8%94-c4

Use latest version of plugin.
Next time create support ticket.

@dom
Btw. on your account does not exists any order for this plugin that could mean you are using it illegally. Please provide your order ID until 3 days to avoid ban.

i have download plugin again and again but it still don't work maybe you fix it in your dev site only. i not use this email for buy your product from market. if you think i Disturb​ you by asking you a lots , you can block me, i create thread because it can help any body that buy this plugin and need to improve it but he don't know how.anyway i can't contact you  with support ticket, i think you will ban me from your market too...if your plugin work well why you not enable user to create categories or post article??? maybe he block me now so bye bye everyone ....

Everyone that has purchased product can create support ticket.

yes i can too but i think not now, i will contact you later or some one will face this problem too, you have been fix but not update plugin in market , now it's not good time for contact you,  this is my feeling, why you check my purchased email? this is the way i afraid. sorry

Please create support ticket