In parallel current sources with capacitors
Improve your question
As @tobalt mentioned, since this is just an analysis question you can combine the three capacitors, in parallel, and replace them with a simpler construct and you can do the same with the three current sources, as they are oriented so that they add together.
Then this is just an RC impedance tied to a single current source. When writing out your work, it would help a lot if you would also point out this observation, as it would save everyone's time having to think that for themselves and then tell you in case you didn't already know it. (I suspect you do know all this. But it never hurts to write more, rather than less, about what you know of a situation.)
So, let's call \$I=3\, I_1\$ and \$C=3\,C_1\$ and \$R=R_1\$. That will help reduce equation clutter without changing the analysis.
Approach
It appears to me that you are looking for an explanation of the simulation results.
Note that the simulation results are in the time domain. Often, the first thing many of us do is first approach the question by thinking about it in the frequency domain. We could do that, but the only real value would be to work out the frequency at which the impedance is at its maximum. That's not needed since you have the frequency, already. So no need to go there. Besides, ratios in the frequency domain are not the same ratios in the time domain.
All you need to do is work out the reactance of \$C\$ at the given frequency (which appears to be remarkably close to \$f=5\:\text{Hz}\$) and put that in parallel with \$R\$. That will give you a new value and an associated angle.
This avoids any use of frequency domain thinking simply because it really isn't needed here.