Hello.
First, let me say that I’m happy to see the idea of Mobilizon and its promising future. The campaign seems to be going well so far. I am not a Facebook user, nor need to create events/groups myself. But I am troubled by all the climate scientists and climate/environment activist groups out there who are using platforms like FB, LinkedIn, Ning, and so one to organize people around critical ecological issues. Being that growth economics, as corporations represent, is the primary driver of climate change and all that it’s bringing, it’s a big dose of bitter irony to see these communities coordinating on the surveillance-capitalist tools of some of the wealthiest corporations in the world. That is seriously wrong on many levels, so if something like Mobilizon (with additional pressure on those communities) can help turn that situation around, then all the better.
And that brings me to the point. I would like to contribute to the cause in a way that may improve your fundraising efforts. I am an editor (native English) and it pained me a little to read the fundraising page, as it wasn’t very polished. Granted it didn’t hurt the first step funding phase, but if you want to connect with more English speakers on a global scale, to keep reaching that bigger funding goal, you want to tighten up the English. Trust me.
Knowing you like Framapad 
… I spent some hours on it yesterday for the first time and made a number of line editing and copy editing suggestions. Gratis! Find it here…
https://mensuel.framapad.org/p/mobilizon
To my pleasant surprise, I checked in today to find many of my corrections and suggestions have been accepted and worked in. That’s no coincidence, so somebody is paying attention even though I’ve not been acknowledged. No worries. Now you know where that came from. 
If Framasoft is interested, I would be happy to continue working on English copy for this project as time allows, beyond just the campaign page. As an editor and native speaker of English (living in Haut-Rhin), who ran a Content Strategy community for several years, among other editorial projects, I have something to offer if you want it. No strings attached.
Last point, for the sake of interests of others… When trumpeting about Mobilizon, I was asked if Framasoft had mentioned anything, or plans for, ‹ anti-harassment › features in the system. Of course, I have no knowledge of Mobilizon development, but I said I would mention it here for the concerned party. Voilà !
But I could surmise from the fundraising text that such considerations might come when it’s certain there is funding for the ‹ federization › of the platform, at which point admin tools are developed? Phase 2, or whatever? In any case, this is why you’ll see such editing suggestion in the pad like this one made for the end of the second paragraph:
This sentence has a word spacing error, but let’s also make it transition better for a strong paragraph finish: ‹ A platform in which privacy, activism, and safety are designed and built right in. › (Note that by adding ‹ safety › to this sentence, we imply the potential for anti-harassment considerations in design without using forceful language like ‹ anti-harassment ›.)
It’s not my position to say what you do with your software. But from a position of advocating ethical software to a larger audience, I would say that finding the right words is wise, sooner than later.
Btw, a short addendum… I realize the workflow for English copy is probably a direct translation of the French version text. While this gets the job done, any editor/translator knows it’s only better than no English at all. A human editor still needs to pass over the text and line edit the copy with understanding of the regional audiences it’s intended. Generally this just means remove word bloat, etc, but it can also benefit from making diction more active, improving transitions across paras and sections, and other such things line editing takes into account. Thus why you’ll see my suggestions are not simply typographic corrections against the translation. Ideally it’s a bit more than that. Bon.