Was going to use J# as an intermediate step between C# and Java, but not much documentation about J#, which appeared to part use the C# .net libraries and otherwise some Java libraries, so not fully compatible with Java nor C#, and otherwise an abandoned language. All up J# not much use in the future, and more hassle than anything else as an intermediate step between C# and Java.
As for other languages like C++, Perl, Ruby and php not certain about the value of these at present. In the main use Excel for calculations and vba to create functions to simplify in cell formula, and otherwise carry out calculations not directly concerned with presentation in a spreadsheet. However Excel is largely used as the source of data and presentation of reports. In that respect Excel/vba is the main programming platform and VB.net seems the most efficient way to re-use code. Though if easy enough to produce Excel Add-in libraries using C#, that may be the way to go. Any case for the immediate future will continue parallel developments in the languages already used.