Hi there Oscar,

First off,

I'm assuming you have made your head a 'character' using the create character node. Trax needs this to establish what set of attributes to key for each pose/clip.

This being so,

I would suggest trying to create shelf buttons that hold your facial expressions.
This is achieved (can be a bit boring to setup but helpful) by selecting the blendshape node and highlighting in the channel box the attributes that are within the blendshape node, eg. (eyebrow up, smile, blink, squint,etc....Always ALL of them) then in the 'Script editor' highlight in similar way and drag (using middle mouse button to shelf....Maybe a custom shelf).

This works best if you have all the blendshape targets set to zero (RESET) before creating each facial pose and shelf button so that the shelf button information is always relative to a default (no facial expressions added) pose.

Try doing this and then key the facial expressions into the timeline as normal. The advantage of doing things this way is that your keys in your animation will be (in graph editor) exactly (timewise) where you created them unlike when you create a pose or clip in the trax editor (which records the keys at wherever you first make the pose/clip. Which means when you want to adjust an f curve in the graph editor later you will be able to indeed find the exact key not a reference of the key (which is almost impossible to adjust and see the changes in real time).

You could then make clips from this animation sequence and start to scale, move, blend and chop up the clips.

Also, I often use the 'Subcharacter' node also to separate for more control things on a face like 'Eyes' and mouth'. This gives a more layered approach to animating a face as often not all facial expressions move in unison but ebb and flow more loosely between extremes (Secondary motion).

Hope this makes sense.
Please let me know how you go.

re Jim