We use this module with PuppetEnterprise 3.8 and Win2008R2 with no issues, but when I run it in our devlab (puppet 4.2 and win 2012R2) I get the following error
Parameter type failed on Windows_env[PATH=%ProgramFiles(x86)%\Java\jre1.8.0_72\bin]:
Invalid value "Reg_expand_sz[]". Valid values are REG_SZ, REG_EXPAND_SZ.
Even though my type is set to REG_EXPAND_SZ -- have you tested this on 2012R2 ? Possible incompatibility ?