Are they rally missing? try selecting a "dot" and ctrl/cmd-T then Enter.
Sometimes the parameters may be set wrong and when migrating the object look like missing (especially when changing the language in-between).
Anyway there may be objects that migrate wrong...
BTW. Try not "migrate" the template but rather make new when stepping up from 16 upwards
- import anything possible but try not using the old lib parts when using the 19...(the background processing relays on optimized objects and does not work if there are any objects not compatible -simplifying objects from AC 18 and before).
Anyway You have to do a big cleanup regarding the building materials etc - so the all composites must be more-less reworked.
I would start from the original template from 19, then imported layers and applied tools to them, then imported the composites and made cleanup to the attributes like fills etc. The last would be importing the favorites (in most cases they migrate ok with standard lib parts when imported)
The last move would be creating the views/clones and layouts (content may be copied - but afterwords you may have to do some additional cleanup in linetypes and fills atributes).
Best Regards,
Piotr