UC Quote module already defines i18n_variables, but as the related settings form doesn't go through system_settings_form(), the i18n module has no grip on those variables. And thus, they don't get translated.
I created a patch to fix this, although I agree with TR and firewing1; it would be better to "fix" i18n, as they state in #896436: Shipping quotes and credit card information strings do not show multi-lingual description message
But for now, the patch will do, for me.
Losing formatting options for those 2 fields isn't really a loss, for me.
|ubercart-make_shipping_i18n_variables_translatable.patch||7.31 KB||Idle||FAILED: [[SimpleTest]]: [MySQL] Unable to apply patch ubercart-make_shipping_i18n_variables_translatable.patch. This may be a -p0 (old style) patch, which is no longer supported by the testbots.||View details|