No, "kompreneble" implies that everybody should understand this. "Of course." On the other hand "understandably" generally means that we can understand something.

• Kompreneble li farigxis kolera = of course he got mad; anybody would.
• Understandably he was upset = we can see why he was mad; and many others in the same situation would have been.

---

Edit:

danielqsc asked below:

So how can we say "understandably" in Esperanto?

A little more context in your question would be helpful. If youre asking how I'd express the idea that I wrote above in Enlglish, what's wrong with: Mi komprenas kial li estis kolera?

---

Second Edit: It's difficult for me to imagine that over-protectiveness is the sort of thing which could be considered reasonable or understandable. By definition, it's excessive.

That aside, my answer to the revised question below is the same. If there's any doubt that your meaning will be understood, reword your sentence.

• Post la tragedia morto de lia unua filo, ni bone komprenis kiam fariĝis pli protektema pri la dua.