"Sofia and Adamo are Esperanto speakers."

Esperantaj parolantoj is totally fine and if it's not accepted by the algorithm, well then report it and it will be. :) It's just that esperantisto is a very common word in Esperanto and English Esperanto speakers is just a way around, because the team decided not to use English word esperantists.

Yeah, it is in beta at the moment, so your feedback is valuable! Hopefully these little wrinkles will be ironed out soon.

Esperanto course is still in its β phase, so don't be turned off by the lack of some equivalent and/or synonymous ways to state a thing in English or Esperanto.

By the way, bonvolu to keep in mind, that “parol·o” (the word which you've suggested) means “speech”; “speaker” is in Esperanto “parol·ant·o”, where the infix “-ant-” could be described in English as a active present nominal participle (someone who performs an action; here: “parol·i”).

No. :) In the case the -ist- suffix is used in the meaning “follower or an idea, movement”, which makes sense, since Esperanto is a created language. The word esperant·ist·o is defined as anyone, who uses this language in the “Deklaracio pri la Esenco de la Esperantismo”.

For other languages, since they don't come with any movement nor idea, it wouldn't make sense to use -ist- in this sense.

So you just say ital·o — “an Italian (person)”, la ital·a (lingv·o) — “the Italian (language)” and ital·parol·ant·o or parol·ant·o de la ital·a — “an Italian speaker” and you just say. german·o — “a German (person)”, la german·a (lingv·o) — “the German (language)” and german·parol·ant·o or parol·ant·o de la german·a — “a German speaker”.

Esperantanoj can be divided into morphemes like that: esperant·an·o·j, where esperant- is a word root signifying the beautiful language we speak, -j is for plural, -o is for noun (as you probably already know) and the affix -an- means “member” (ĥor·o — “choir” & ĥor·an·o — “chorister”, polic·o — “police” & polic·an·o — “police officer”) or “inhabitant” (Pariz·o — “Paris” & pariz·an·o — “Parisian”, insul·o — “island” & insul·an·o — “islander”).

But remember that esperant·an·o is a very uncommon word and in this case you should probably go for esperant·ist·o (where -ist- is for a profession or a follower of some idea).

By the way, the word esperant·o itself came from a pen-name, which Zamenhof (the creator of Esperanto) used: Doktor·o Esper·ant·o. On it's own it can also mean in Esperanto esper·ant·o, where the root is esper- related to hoping (esper·i — “to hope”) and -ant- is for active present participle, and so esper·ant·o means literally “hoping one, one who is hoping”, and that's where the letter “t”, you've been asking for, came from. :)

Your reasoning isn't valid.

The word parol·i means “to speak” and parol·o means “speech”; “speaker” is in Esperanto parol·ant·o, where the infix -ant- is the ending of the active present nominal participle (someone who performs an action; here: parol·i).

That's exactly right. :)

Hey! No need to shout. Let us behave here.

Answering your question: yes and no. Sofia is a personal name. You may therefore treated as being outside and independent of any language — it's somebody's name therefore you may use it in Esperanto to refer to that person.

But you may also treat is as proper Esperanto name. Languages translate personal names adjusting them to their own rules of phonology and orthography. Nowadays many languages tend to leave foreign names unchanged (maybe except for names of royals) but Esperanto has a strong tradition of esperantisation of names, either by using long-established forms or following their patterns.

Sofia is an Esperanto form of the female name existing in many different languages, e.g. English “Sophie”, Greek “Σοφία”, Hungarian “Zsófia”, Russian “София”, Icelandic “Soffia”, Polish “Zofia”, Georgian “სოფჰიო”, Maltese “Sofana” and many more. Many people bearing any version of the name would choose to use the form Sofia in Esperanto.