For the moment, the only ways to define a locale for formatting numbers (esp. decimal and thousand separators) is by using the general option (hence fixed) or an OUT tag (hardcoded).

Our concern is that we produce documents in 25+ languages, for potentially 35+ countries, leading to a huge number of combinations. Having only fixed/hardcoded formats is therefore a problem.
Also, we use a lot of variables to manipulate our data.

Consequently, having a good TEXT function would be of great help to us. The possibility to specify a locale (language+country), or at least a language, in the format of the TEXT function would be a great relief, because we would be able to format our numbers inside SET tags, with all the flexibility we need.
Unfortunately, I could see that using languages in front of formatting (e.g., “[en]#,##0.00”) does not work in Windward, despite this syntax is common with Excel.

Optionally, if we cannot specify a locale or a language for a format, then we should at least be able to specify the decimal and thousands separators in the TEXT function.

This idea may be seen as a complement to https://windward.uservoice.com/forums/248503-windward-core/suggestions/45448441-property-or-parameter-for-defining-the-decimal-sep.