Open your browser console and then save a translation, does anything show in the error console? Have you tried disabling mod sec and then save a translation?
this happens to me in phrases and template css they do not update me, but they do not give me any error.
but in template PAGE_CONTAINER I enter code and if you update me
Everything is customizable in XF2, just seems something is wrong with your install. You can open a ticket in your customer area, https://xenforo.com/customers/support
this will have something to do with this it came to me when I updated to xenforo 2 in a subfolder
The following warnings were detected when verifying that your server can run XenForo:
1.Your server has disabled a core PHP function exec via the disable_functions directive in php.ini. This may cause unexpected problems in XenForo.
2.Your server has disabled a core PHP function escapeshellarg via the disable_functions directive in php.ini. This may cause unexpected problems in XenForo.
3.Your server has disabled a core PHP function proc_open via the disable_functions directive in php.ini. This may cause unexpected problems in XenForo.
4.Your server has disabled a core PHP function popen via the disable_functions directive in php.ini. This may cause unexpected problems in XenForo.
Then your server will not meet the requirements to run XF2. If you wanted to ever upgrade to XF2 you would need to find a host that meets the requirements.