IFS is multi-dimensional and I am not aware of any significant code part changes from 9 to 10.   

For the reporting, anything that is defined in IFS is accessible for reporting.   The report tool utilized as well as the time that may be needed from a tech resource will vary.   

It is difficult to give a more direct answer without more information regarding your setup and business practices.

in the current status our consultant created a different company for each production unit, because the owner need trial balance and balance sheet for each production line.

but we can solve this issue if system has the ability to generate the trial balance in for many level.

Example

the company name is XYZ (the legal entity), so system will create trial balance and balance sheet without any difficulties.

we will create string code production line, and we need system to create trial balance and balance sheet.

in the manufacturing module, there is a separate process for each production line.

please advise.

Code parts could be used to segment production lines within one company.   There are many variables you would need to discuss with your consultant.  Reports would likely be custom.    To make these large changes could get as involved as an implementation.   Your organization needs to decide if it can tolerate the time and expense vs a simple version upgrade.