Looks like it'll be tricky for everyone to be able to attend.
Looks like it'll be hard for everyone to make it (on that day).
It seems like it may be difficult to find a time we can all meet.
参加する = attend
to make it = 行けること;参加できること
on that day = その日
難しい = tricky; hard; difficult
”It seems like it may be difficult to find a time we can all meet.” =>
「皆が会える時間を見つけるのは難しいそうかも知れませんね。」文字通りの翻訳です