Yes, PopcornFX Renderer Mesh's default blending modes are only solid and additive.
Alpha Blend is not in the default list for Mesh particles because the trivial way to implement it is to depth-sort all triangles of all meshes, which, as you can imagine, can be very costly ! and also depends on the Game Engine.
But, PopcornFX Plugins have some ways to let you override the default particle Materials:
In Unreal Engine you can change the entire material by your own: https://wiki.popcornfx.com/index.php/UE4/Class_PopcornFXEffect#Effect_Editor
In Unity you cannot change the blending mode (yet), but you can change the shader code: https://wiki.popcornfx.com/index.php/Custom_Shaders_(Unity_Plugin)
So, for example, if you set a Masked/AlphaCutoff material, you should be ok, because this "blending" actually usually writes depth, so it is sort-independent.
If you have a convex mesh, and disable double-sided surface, an AlphaBlend material might be able to work, but as we do not sort mesh instances either, there can still be artifacts.