Translation of the Data

Some paremters are already translated : Profile, IndicatorDefinition, Periodicity, Privacy, Report, ReportCategory, ...
It is easy to extend : just addin the class definition.
You could extend this functionality but will have translate all values in the translation file.

The automatic translation of fields is largely out of scope. Project'Or RIA is not Google
The idea to multiplicate the fields to have translation is also out of scope : the multilanguage concerns only the GUI, not the Data.
The scope is to be able to provide a tool as wide as possible, so that teams from various conties can use it. It is not devoted to provide translation to teams working together in different languages : all majors companies with such problems have solved it for long : just fix one work language for the whole company

By the way, do you think a multilingual manual is possible ?

Everything is possible. All depends on the effort you want to spend on it.
On my side, it is yet a very hard work and time consuming activity to maintain user manual in only one language. I will not focus on translating it ... and I would be able to translate only to french, as I don't know a word of german, spanish, portugese, russian and chinese

I saw that the slides are up to 16MB, perhaps it could be a problem with 4-5 more language...

It is not the most blocking point, as space is required for pictures (that would not be translated), and text represent only a small part of the total size.

(Another btw, there is a typo slide 181, "Fro instance")

Fixed.
thanks.