Here's a list of issues found after comparing summary `extract_html` fields from 1.2.0 to 1.3.0 (MCS commit b0be98c). (checked ar - es so far)
=== Issues
[] `scribunto-error` as first paragraph selected for [[ https://bg.wikipedia.org/api/rest_v1/page/html/%D0%92%D1%82%D0%BE%D1%80%D0%B0_%D1%81%D0%B2%D0%B5%D1%82%D0%BE%D0%B2%D0%BD%D0%B0_%D0%B2%D0%BE%D0%B9%D0%BD%D0%B0 | one article in bgwiki ]]. We should consider removing `span.scribunto-error` from the DOM before selecting the intro paragraph.
[] We should also consider not going into any subsections, in the rare corner case where the lead section has a subsection. (The new Parsoid `section` elements are/can be nested.)
=== Should be fixed on the Parsoid level or onwiki
[] Infobox syntax shown [[ https://bn.wikipedia.org/api/rest_v1/page/html/আলী_ইবনে_আবু_তালিব/2837813 | one article on bnwiki ]]
[] `books.google.com/books?isbn=0810864908` shown in [[ https://ar.wikipedia.org/api/rest_v1/page/html/%D8%A3%D9%85%D8%A7%D8%B2%D9%8A%D8%BA/26896137 | one arwiki article ]]
=== To be fixed onwiki
[] I recommend we encourage template editors to use the `noexcerpt` class for things which should not appear in the summary output:
[] cswiki: `[zdroj?]`: [[ https://cs.wikipedia.org/api/rest_v1/page/html/LP_(zpěvačka)/15696307 | cs:LP_(zpěvačka) ]]
[] dawiki: `[kilde mangler]` [[ https://da.wikipedia.org/api/rest_v1/page/html/Solhverv/8975374 | da:Solhverv ]], [[ https://da.wikipedia.org/api/rest_v1/page/html/Revselsesret/9250916 | da:Revselsesret ]], [[ https://da.wikipedia.org/api/rest_v1/page/html/Marilyn_Monroe/9313326 | da:Marilyn_Monroe ]], [[ https://da.wikipedia.org/api/rest_v1/page/html/Lily_Broberg/9294616 | da:Lily_Broberg ]]
[] eswiki: `[¿cuál?]` [[ https://es.wikipedia.org/api/rest_v1/page/html/Avril_Lavigne/104684337 | es:Avril_Lavigne ]]
[] eswiki: `[cita requerida]`: [[ https://es.wikipedia.org/api/rest_v1/page/html/Poder_legislativo/105112605 | es:Poder_legislativo ]]
[] Should be a list after the first paragraph: [[ https://ca.wikipedia.org/api/rest_v1/page/html/Anarquisme/19283010 | ca:Anarquisme ]]
=== Minor issues, some of which should probably be fixed in MCS
[] too many punctuation/whitespace characters (usually a result of stripping parentheticals or IPAs)
[] double commas (`,,`): [[ https://en.wikipedia.org/api/rest_v1/page/html/Paul_McCartney/822867780 | en:Paul_McCartney ]], [[ https://da.wikipedia.org/api/rest_v1/page/html/Blasfemi/9104429 | da:Blasfemi ]], [[ https://es.wikipedia.org/api/rest_v1/page/html/Will_Smith/105231673 | es:Will_Smith ]], [[ https://es.wikipedia.org/api/rest_v1/page/html/Mar%C3%ADa_I_de_Escocia/105110472 | es:María_I_de_Escocia ]]
[] comma before semicolon (`,;`):
[] double spaces (` `): [[ https://en.wikipedia.org/api/rest_v1/page/html/London/822677492 | en:London ]],
[] space before comma (` ,`): [[ https://da.wikipedia.org/api/rest_v1/page/html/Prins_Joachim/9341511 | da:Prins_Joachim ]], [[ https://es.wikipedia.org/api/rest_v1/page/html/Cristiano_Ronaldo/105191364 | es:Cristiano_Ronaldo ]], [[ https://es.wikipedia.org/api/rest_v1/page/html/Grecia/105177728 | es:Grecia ]]
[] space before semicolon (` ;`): [[ https://es.wikipedia.org/api/rest_v1/page/html/C%C3%A9lula/105100890 | es:Célula ]]
[] consider not stripping `()`
[] from paragraphs after the first paragraph (e.g. in `<li>` elements): [[ https://en.wikipedia.org/api/rest_v1/page/html/Suit/822913926 | en:Suit ]], [[ https://da.wikipedia.org/api/rest_v1/page/html/Kulstofkredsl%C3%B8b/9351225 | da:Kulstofkredsløb ]]
[] with contents in bold `(<b>foo</b>)`: [[ https://el.wikipedia.org/api/rest_v1/page/html/%CE%95%CF%85%CF%81%CF%89%CE%BC%CF%80%CE%AC%CF%83%CE%BA%CE%B5%CF%84_1987/6542146 | el:Ευρωμπάσκετ ]], [[ https://es.wikipedia.org/api/rest_v1/page/html/N%C3%BAmero_%C3%A1ureo/105154269 | es:Número_áureo ]]
[] with contents in `("")`: [[ https://da.wikipedia.org/api/rest_v1/page/html/Syre/9236379 | da:Syre ]]
[] extra artifacts after IPA removal:
[] `()`: [[ https://de.wikipedia.org/api/rest_v1/page/html/Bayern/173351784 | de:Bayern ]]
[] `?`: [[ https://es.wikipedia.org/api/rest_v1/page/html/Guatemala/105160210 | es:Guatemala ]], [[ https://es.wikipedia.org/api/rest_v1/page/html/Corea_del_Norte/105116741 | es:Corea_del_Norte ]], [[https://es.wikipedia.org/api/rest_v1/page/html/Corea_del_Sur/105093661 | es:Corea_del_Sur ]], [[ https://es.wikipedia.org/api/rest_v1/page/html/Mesoam%C3%A9rica | es:Mesoamérica ]]
[] title missing: [[ https://de.wikipedia.org/api/rest_v1/page/html/Stuttgart/173449180 | de:Stuttgart ]]
[] Remove loundspeaker icon: [[ https://es.wikipedia.org/api/rest_v1/page/html/Leonardo_da_Vinci/105247043 | es:Leonardo_da_Vinci ]], [[ https://es.wikipedia.org/api/rest_v1/page/html/Charles_Darwin/103684327 | es:Charles_Darwin ]]
[] picked wrong paragraph: [[ https://es.wikipedia.org/api/rest_v1/page/html/Cambio_clim%C3%A1tico/105201387 | es:Cambio_climático ]]
=== Nice to haves
[] would be nice to also include the paragraph immediately following the first when the end of the first paragraph ends with `:`: [[ https://cs.wikipedia.org/api/rest_v1/page/html/Ohm%C5%AFv_z%C3%A1kon/15567838 | cs:Ohmův_zákon ]], [[ https://cs.wikipedia.org/api/rest_v1/page/html/Archimédův_zákon/15693096 | cs:Archimédův_zákon ]], [[ https://cs.wikipedia.org/api/rest_v1/page/html/Příslovce/15397768 | cs:Příslovce ]], [[ https://da.wikipedia.org/api/rest_v1/page/html/Idealgasligning/8516662 | da:Idealgasligning ]], [[ https://es.wikipedia.org/api/rest_v1/page/html/Resistencia_el%C3%A9ctrica/103807716 | es:Resistencia_eléctrica ]]
[] still has IPA: [[ https://ca.wikipedia.org/api/rest_v1/page/html/Albert_Einstein/19604902 | ca:Albert_Einstein ]], [[ https://ca.wikipedia.org/api/rest_v1/page/html/Charles_Robert_Darwin/19598946 | ca:Charles_Robert_Darwin ]], [[ https://cs.wikipedia.org/api/rest_v1/page/html/Visegrádská_skupina/15533497 | cs:Visegrádská_skupina ]]