If you are talking about what we call Gift Card (gifuto-kaado) in Japan, where for example, a 500 hundred yen worth coupon will allow the user to purchase anything worth that price, yes, it is extremely common to buy them.

Quite often, cash is considered as something "too obvious" so just to show modesty, the sender would purchase Gift Cards and send these Cards to someone as a means of celebration or appreciation.

It is for the 60th birthday of a relative and I want to be sure that a) it is appropriate and b) the T&C just in case she is not sure what to do with the electronic GC and/or needs to refund or if GC has any restrictions.

The older generation may not fully understand how the electronic gift cards work.

Electronic gift cards are not as popular as "(paper-based) gift card/gift certificates" in Japan, except for online shop-specific gift vouchers sent via e-mail. So unless you send her some electronic voucher redeemable at a shop that you KNOW she shops at online, it is likely that the recipient may not know what to do with it. The way I undersand it, above posts have been talking about gift vouchers and gift certificates, the common ones in Japan being paper-based.