That made me laugh! If forced to learn an IAL[1] I'd probably choose Solresol[2] because what sane person could resist the chance to yodel their complaints to Customer Services?

Or, if "terse and efficient" are an immovable part of the specification then I'd suggest Ithkuil[3] ... or maybe Rust?

[1] International Auxiliary Language

[2] https://www.ifost.org.au/~gregb/solresol/sorsoeng.htm

[3] http://www.ithkuil.net/