The mishna said in the 3nd chapter of Eruvin mishna 1-2:
מְעָרְבִין לְנָזִיר בְּיַיִן וּלְיִשְׂרָאֵל בִּתְרוּמָה ... מְעָרְבִין בִּדְמַאי
We can make an Eruv for a nazir by wine, for Yisroel by teruma, with Demai. The demai is not really allowed for a not poor neeman man. But it is good for Eruv.
We can assume that Egg Matsa is not considered as prohibited as Chomets, some people do not eat this by minhag. May be that it is similar to Demai from this point of view. The cases of Nazir which can ""Lehishael" and truma which can too, are perhaps an additional proof for the Egg Matso minhag which can also be nish'al. I heard that the Steipeler זצוק"ל was stringent to eat "not Gebrocht". When his spouse deceased, he was invited to his daughter. When he saw that she made stringent efforts to make not gebrocht, when in her home they was eating Gebrocht, the Steipeler has decided to make Hatarat nedarim and started to eat gebrocht.
So Eruve Chatserot with eggs Matsot are apparently good enough . Nobody think that egg Matsa is prohibited, the minhag may be changed by hatarat Nedarim, nobody is nishba mehar Sinai. Efshar Lehishael.
I am duty to @Double AA for indicating this post.