I did some research on a few missing dates and found the following:
the whole french tour of 1977 was announced in France (Best magazine for example) but I'm not sure that all the dates took place.
at least, the first concert (20/04/1977 Le Havre) happened, the name of the venue is Petit Theatre. I found a confirmation on this Facebook page: https://fr-fr.facebook.com/rockinlehavre
where you can even read an article announcing it (of course, it's in french) ! a guy said that 48 tickets were sold.
the concert on 23/05/1977 in Paris took place in Le Bataclan. It's doubtful that they played in april.
they played in Montréal on 16/04/1978 in a place called El Casino. I found the date on this website: http://rocktourdatabase.com/node/1197
(I'm not sure that the site is reliable but I'm sure that they played in Montréal in 78).
I found the Boston dates for the same tour: 23 and 24/03/1978 in The Rat club, here: http://www.bostongroupienews.com/GigList.htm
they played in Lyon (Palais d'hiver) on 14/11/1979 and in Saarbrücken (Aula der Uni) on 23/11/1979 (I found 2 tickets of the events).
there's a second concert at La Mutualité in Paris on 01/03/1983, following the concert of the previous night. this was confirmed, on the French Stranglers forum, by a member of the French SIS who attended this show. by the way, Maubert Mutualité is the name of the next tube station, the name of the venue is Palais de la Mutualité or simply Mutualité (it's not really a palace !)