How to handle Artist and Albumartist

[aliasname]

stuck again ....
wanted to so something like this
prefix field1 field2 field3 suffix in tagformat where fields 2 & 3 are optional and wont be present all time.
eg. ALBUM <1970 remaster 2009> for a remaster
vs. ALBUM <1970> being the original release
stripping the second 1970 from the second example now works using the tagupdate.
but I can't get the suffix being processed. If use in tagFormat it can't work since if field3 is missing it's suffix is also missing.
So I decided to put the following into tagValue
Date={Date, Albumversion, Releasedate}
minimserver then moans about Date being not allowed in tagValue
not to mention that I can't define spaces, but it would have surely allowed to use prefix and suffix in tagFormat this way.

I'm lost. there's too many differnt sections when one could define things which more or less to influence each other, or better said, you must guess why something doesn't work even if reading the docs since the thrown errors explain only that something's wrong but not what's excatly wrong. For example I now get 'incorrect Tagname Date in Date.merge. Date is a valid tagname and .merge is a valid action according to the docs. Any idea where I'm wrong?