We support display of non-Arabic number systems. We should add support to parser functions for so that "{{#expr: {{CURRENTYEAR}} 10}}" (see example in Bug 31371) will work.
Ideally, wikitext like "{{#expr: ২ ৩}}" would work as well.
https://bn.wikipedia.org/wiki/User:MarkAHershberger/sandbox
Known workaround, use {{formatnum:{{{1}}}|R}} in template - e.g. {{#expr:{{formatnum:{{CURRENTYEAR}}|R}} 10 }}