In my experience (which includes producing multi-national documents and printing in Eastern block, China) there isn't any accurate conversion software in terms of language conversion - e.g. English to German OR the electronic characters required to transfer an electronic document between devices and operating systems. Without getting too technical the reasons for this are:
1) Language / dialect is localised so there may be 5 versions of the English word 'castle' in German. Conversion software isn't sophisticated enough to pick up the nuance of context in the sentence so it will make a choice based on an algorithm and more often, substitute the nearest (wrong) word.
2) Text (representation on screen) is handled within the individual operating system whether it be Mac, Windows or a mobile OS and to some extent by the installed software applications (for font substitution). If the characters used in the original work are not present on the receiving device then they wont appear (or a substitution will occur).
As a simple example: I have the official Microsoft Office for Mac including MS Outlook (mail) client. I can create a text signature within Outlook which looks great on my Mac email message but when a Windows client receives it, the leading and font change and it looks poor, even though they are also viewing it in MS Outlook. The reason is that I have used Helvetica (Mac OS) which is not the same as Helvetica (Windows) so re-formatting occurs on screen.
To get around this I have reset my email signature in MS Verdana and built it in HTML myself to control the leading. Works OK on Windows now.
There are some things you can do on the Mac end which will help and are part of the practice that gets me over these issues.
By default, the full global language support kits will NOT be installed on your Mac due to pre-shipping localisation and Ram considerations, but they are free from Apple and often bundled on the installation disc / download. Stock Macs tend to ship with minimum Ram (bad) and a generous font bundle (good) placed in the system folder (bad). These will all be available to every application you launch creating a heavy hit on performance so we need to do a bit of housekeeping first.
- Install a good font manager like Linotype Font Explorer Pro and port all but the base set of Mac OS fonts to this. You should only have 30 or so fonts load now at startup and your boot time will shorten. FEP is clever software and will load fonts only as applications require them.
Note: Apple's shipped FontBook software support has severe limitations and should not be relied on professionaly.
Now go to system preferences and 'add the localisation, for the countries that you need. Generally I have English, Spanish, French and German running. This will ensure that the additional glyth's and characters are available within the OS (and special characters palette / your keyboard). You can also turn some unused default languages off here (like Chinese) to save RAM.
Max your RAM out if you can afford it. This helps with rendering and app launch (which makes language conversion quicker).
Note: some programmes can adversely affect use of installed language kits. Quark Express had a problem with Cyrillic languages due to poor support back in the day. Adobe Indesign including CS4 should be fine but check the preferences fully to ensure that there are no language or character restrictions operating.
for copy transfers (between offices) use a common font across your groups that is Windows standard e.g. MS Verdana or Arial and exchange documents in Microsoft Word. Reason being, almost everyone commercially will have access to this so you will now be working to a common platform and common font. Half the battle. And Microsoft has good support for languages built in.
at this point, if I am including a language conversion (within the output) I send the MS Word text document to the recipient country and have it checked by someone locally for corrections and dialect. There are services that will do this for you if staff are too busy.
on return of this document to your Mac (via email, Dropbox etc) you now have the correct, signed-off text in a Word document with all characters intact. Now work up your Indesign layout checking text back against the Word file as you go.
Indesign can re-set the text in whatever font you choose as long as the font supports your required languages (many free fonts don't - you will have to experiment or Google for recommendations). Frutiger is a good example of a modern sans with good language support.
- final trick, in Indesign once you are ready to print, duplicate your document and called it filename_converted *. Now select your text boxes and go Menu / Type / Create Outlines. This will essentially lock your typesetting as bitmaps including all characters, spacing, leading etc. Now export this as a PDF (you will notice in this process that no fonts are packaged because there aren't any). This PDF will render on Windows or Mac (and mobile) including all characters and can be used for repro-graphic print companies located abroad. I printed the below job in Polish / Poland this way. No text or character issues.
- The caveat and reason for saving an edit file is that the text in the supplied PDF will NOT be editable by the recipient. This is the cost of locking it down multi-platform. If a recipient needs the editable text, send it separately in Verdana / MS Word .doc format.
Hope this helps, not a quick fix but has worked for me since Quark / Indesign 1 ('95 / 99) on a Mac.