Hello @Alvaro
Indeed, it seems I was not clear enough
I created a template to apply only to tiddlers with a specific tag “MyTag” ; For that, I used the code 
<$list filter="[all[current]tag[Contact]]">
{{||ContactInformationTemplate}}
</$list>
if I open a tiddler tagged “MyTag”, it works.
But if I transclude the tiddlers (directly oor by search as you did), the default template is applied ; it makes sense as the containing tiddler is not tagged with MyTag and the fields are in the transcluded tiddlers, not the one I am currently reading
MAYBE I am wrong and it is necessary to ALWAYS precise the template to apply but I thought (hoped ?) that it would not be necessary ?
Is there a way for that to works ?
Real example :
Here is a tiddler : [[JohnDoe]] ;
- it has fields such as phone, address,…
- it has a tag Contact
I create a template tiddler [[$:/szdavid/TiddlerTypeTemplates/Contact]] tagged $:/tags/ViewTemplate
I add the following code in it :
<$list filter="[all[current]tag[Contact]]">
{{||ContactTemplate}}
</$list>
and the tiddler ContactTemplate has this code :
<h2>{{!!title}}</h2>
<ul>
<li>Phone : {{!!phone}}</li>
</ul>
Now, when I open [[JohnDoe]], it displays correctly.
But if I transclude it in any tidller, it does not :
- {{JohnDoe}}
{{{ [tag[Contact]]}}}
Thanks