Bulk import cover arts

Hello. I have a lot of files with similar name structure:

title.tvepisode_date.ext

and the same number of covers (their names are equivalent to tvepisode.jpg).

How to import right covers for files based on the part of filename?

Using the filename is not the optimum approach.
If you have a structure in the filename then you should first convey that structure to tag fields and import the data into the fields.
e.g.
Convert>Filename-Tag
%title%.%TVEPISODE%_%dummy%

Then use an action of the type "Import cover from file" and enter as filename:
%TVEPISODE%.jpg

Thanks. Please help with following. I have files with name structure: Artist_Publisher_Episode_Date.ext

'Episode' sometimes = Unknown Episode

I try to write 'title' tag like this:

%artist% (%publisher% / $if(%episode%="Unknown Episode",%date%,%episode%))

What's wrong here? mp3tag always writes %date%.

There is not really a field called DATE. Some players/taggers create this.
The only fields that carry date information are YEAR or RELEASETIME.

It its not quite clear how you get a TITLE from the filename.

Edit: I had to think a little - could it be that the syntax for $IF is wrong? If you want to compare 2 strings then you have to issue a $eql() statement:
$if($eql(%episode%,'Unknown Episode'),%date%,%episode%)
It is not possible to use the = as comparison operator.

I get tags %date%, %episode%, %artist% and %publisher% from filename at first of course. mp3tag extracts these tags correctly, inc. %date%.

The problem is somewhere in syntax I think.

If I use %artist% (%publisher% / $if(%episode%="Unknown Episode",%date%,%episode%)) mp3tag always writes %date% ...

if I use %artist% (%publisher% / $if(%episode%<>"Unknown Episode",%episode%,%date%)) it always writes %episode% regardless of episode name (even it is Unknown Episode).

That is what I gathered after I thought a little. Please see the edit of my previous post.

Thanks. It works ok now!