While the Client Deployment Wizard (CDW, the tool you're using from "Home -> Commnon Tasks -> Install Protection to client computers") is able to detect processor architecture, it sounds as if it is unable to detect the language of the target machine (as demonstrated by it pushing the CZE SEP client to your EN Windows machine).
As a workaround, you could try exporting the client install packages to an installation file (http://www.symantec.com/docs/HOWTO81164), and pushing them out using the Push Deployment Wizard (found in the SEP Part_2 media under Tools -> PushDeploymentWizard):
http://www.symantec.com/docs/TECH183172
As the Push Deployment Wizard lets you choose exactly which execuatable to push, you can always be sure you have the right language version going to the right machine. The only difference is that you will also have to ensure you're pushing the correct cpu architecture package as well, as this wizard does not detect the difference between x86 and x64.