I have modified DefaultEngine.ini (you can change also from HoudiniEngine -> Plugin Settings)
[/Script/HoudiniEngineRuntime.HoudiniRuntimeSettings]
HoudiniExecutable=HRSHE_HoudiniIndie
CustomHoudiniLocation=(Path="C:/Program Files/Side Effects Software/Houdini 19.0.531/bin")
string HoudiniVersion = "19.0.531";
Version mismatch might be the reason why UE5 is not able do discover matching HE.
If setting Houdini Location won't help and you are using engine from launcher you will need plugin binaries for 19.0.531.
I'm not sure why plugin HoudiniEngine-v2.0.8-H19.0.531-UE5.00-preview2.zip is changed to 554 version.
I hope this will help.
Cheers.