I know in Germanic languages, the same thing happens.

English:
That is the same umbrella that I found on the bus.

German:
Das ist der gleiche Schirm, den ich im Bus gefunden habe.

Not only Germanic languages, but look at French:
C'est le même parapluie que j'ai trouvé dans le bus.

acdibble:I know in Germanic languages, the same thing happens.

English:
That is the same umbrella that I found on the bus.

German:
Das ist der gleiche Schirm, den ich im Bus gefunden habe.

Not only Germanic languages, but look at French:
C'est le même parapluie que j'ai trouvé dans le bus.

Mmmm.... Probably since relative clauses and noun clauses (specifically the ones using "that/ke", e.g. I know THAT he is a monkey; I think they're called "subject/adjective compliments") come from the same root in linguistic evolution for Indo-European languages (not that I really know)....

acdibble:I know in Germanic languages, the same thing happens.

English:
That is the same umbrella that I found on the bus.

German:
Das ist der gleiche Schirm, den ich im Bus gefunden habe.

Not only Germanic languages, but look at French:
C'est le même parapluie que j'ai trouvé dans le bus.

Add Polish to the list:

To jest ta sama parasolka, którą znalazłem w autobusie.

acdibble:I know in Germanic languages, the same thing happens.

English:
That is the same umbrella that I found on the bus.

German:
Das ist der gleiche Schirm, den ich im Bus gefunden habe.

Not only Germanic languages, but look at French:
C'est le même parapluie que j'ai trouvé dans le bus.

I generally avoid using the same word in a sentence; the appearance of the word "that" twice would irk me. I would say:

I found that same umbrella on the bus.

Miland:

komenstanto:I find commas in general to be fairly interesting in Esperanto. I would like to discuss commas more and the words that are magnetized to them.

In PMEG we have (I translate):
"A comma is used inside sentences, where it can be natural to pause a bit, for example before a sub-clause, and in the place of the words "and" and "or" in enumerating a number of things. A comma is sometimes used instead of a full stop between main clauses, which belong together in some way."

Thus the motive is similar to that in English: indicate a small pause.

komenstanto:I was wondering if one generally would speak a sentence like that, or only write it.

This is a matter to be resolved by experience. Go to an Esperanto meeting and listen for Jen..! A suitable substitute might be to read some of the Esperanto-language forum.

How can I be sure the Esperantists are using proper Esperanto on the forum? I prefer just to study the PMEG and discuss it in English, to have that solid text as a reference rather than taking a stranger's word for it.

You are still taking a stranger's word for it in the English forum. If ceigered says something, and I say something else, and geo63 says a different thing than either one of us, how do you know who to believe?

You can discuss PMEG on the Esperanto forums just the same as you can here.

In the new lernu, forum postings will likely contain an indicator of the poster's language level, so you will have some degree of assurance that this person knows what they're talking about. Until then, you just have to read the forums long enough to get a sense of who is giving accurate information and who isn't. And forum readers are usually quick to correct someone who is giving advice that isn't correct (though in a nice way, of course; no one here intentionally gives bad advice).

erinja:
In the new lernu, forum postings will likely contain an indicator of the poster's language level

I wonder how that will be decided?

erinja:.. If ceigered says something, and I say something else, and geo63 says a different thing than either one of us, how do you know who to believe?

That's easy. Believe Erinja. She's free to question this my judgment, of course.

Chainy:

erinja:
In the new lernu, forum postings will likely contain an indicator of the poster's language level

I wonder how that will be decided?

the site has an exam system!

Chainy:

erinja:
In the new lernu, forum postings will likely contain an indicator of the poster's language level

I wonder how that will be decided?

Here's one possibility: regularly and enthusiastically singing La Espero will be de rigueur. Note that it must be enthusiastic; just going through the motions won't do. Opposing the practice will be a sign of a potential kabeonto. Of course, such people might know the language well, but who needs bad examples?