Simple answer : NO WAY !
Must be same binary informix distribution and same Informix version including patch.
If they upgrade the 11.50 to 11.70 or above, can be achieved thru ER
There is no need to upgrade the 11.5 to use ER
As Paul said, check archecker.11.50 probably allows to extract data from the archive.I remember this functionality was not in 10 not 11.10 and was introduced in 11.50 XXX ?
Syntax is archecker -b -.......
I think it has got tighter, but I have restored with minor version differences in the past.