I think there's a few issues with your command line, some of the switches aren't variables, some of them you need to escape with quotation marks.
To install the features you listed, you need the following features switch:
SQLEXPR_x64_ENU /QS /IACCEPTSQLSERVERLICENSETERMS /Action=install /INSTANCENAME=XYZ /FEATURES=SQLEngine,REPLICATION,SNAC_SDK /SAPWD="n:4Y2cX=W3/I" /SECURITYMODE=SQL /TCPENABLED=1 /NPENABLED=0
Ensure that the feature list does not have a space and any reserved characters are escaped in quotes. The MSDN documentation is unclear, it gives an example with a space as you've tried to use, but the page actually states:
/PARAMETER="value1" "value2" "value3" for all multiple-value parameters. Using double quotation marks is recommended, but required if the value contains a space
/FEATURES, which is a multivalued parameter, but its format is /FEATURES=AS,RS,IS without a space, comma-delimited
Ensure you have the casing correct also. See here for detailed guides on using the command line switches for a SQL installation.