Depends on whether u already have those couple chars. Seriously, I don't fancy the idea given by the video for elwin and liana. (ie, he already have both chars, but just for 10 more liana shards, he suggested farming 50 elwin shards to exchange for 60 liana shards).
But of course, if you already have most of the ssrs in the couples banner like him, it can be a way to use the cp token if you don't have any other use.
Eg, I already have leon, lana, elwin, liana and listell but no landius. I pull on the landius/listell and bingo!, i pulled a landius. Since I have all ssr in the event already, I use 50 leon shards that I previously stocked and trade for 60 lana shards, so that the cp token is not wasted.
The event's main draw is to get the couple char u are missing if you have the other half of the couple.
Another scenario:
I have Leon, Lana, Listell. No elwin, liana, landius.
I decided to pull on elwin/liana (while hoping to get liana). I landed on elwin, and it gives a cp token. I trade 50 listell shards I had farmed plus the cp token for landius.
I continue to pull on elwin/liana banner and so unlucky, I pulled elwin again. Since I already have elwin from the earlier pull, I get 50 elwin shards from this pull and a cp token. I trade the elwin shards + cp token for liana.
This is why I call this event 'a dream come true' event, since its possible to fill up all your missing core chars in this event.
Tentative banner schedule for SEA
https://www.reddit.com/r/langrisser/comments/cshebu/upcoming_banners_for_langrisser_sea/
Although it states the couples banner MIGHT happen on jan 21st, its likely that SEA might push the couple banner to feb to make it more 'meaningful'.