To split by date and event columns - regex

Question

I am trying to split by date and event columns. It is impossible to search for ". " some lines contain multiple sentences ending with ". " Also, some lines don't start with dates. The idea of ​​the script was to use a regexp to find lines starting with the fragment "one or two numbers, space, letters, period, space" and then replace "point, space" with a rare character, for example, "#". If the line does not start with this fragment, then add "#" to the beginning. Then this array can be easily divided into two parts by this symbol ("#") and written to the sheet.
Unfortunately, something went wrong today. I came across the fact that match(re) is always null. I ask for help in composing the correct regular expression and solving the problem.
Original text:
1 June. Astronomers report narrowing down the source of Fast Radio
Bursts (FRBs). It may now plausibly include "compact-object mergers
and magnetars arising from normal core collapse supernovae".[3][4]
The existence of quark cores in neutron stars is confirmed by Finnish
researchers.[5][6][7]
3 June. Researchers show that compared to rural populations urban red
foxes (pictured) in London are mirroring patterns of domestication
similar to domesticated dogs, as they adapt to their city
environment.[21]
The discovery of the oldest and largest structure in
the Maya region, a 3,000-year-old pyramid-topped platform Aguada
Fénix, with LiDAR technology is reported.
17 June. Physicists at the XENON dark matter research facility report
an excess of 53 events, which may hint at the existence of
hypothetical Solar axions.
Desired result:
Code:
function replace() {
const sheetName = "Sheet1";
const sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(sheetName);
const lr = sheet.getLastRow();
// const range = sheet.getRange(2, 4, lr - 1);
const range = sheet.getRange(100, 4, 5);
const arr = range.getValues();
const newArr = [];
const re = new RegExp("^([0-9]{1,2}\s[a-z]+\.)\s");
for (let i = 0; i < arr.length; i++) {
const match = arr[i][0].match(re);
if (match == null) {
let newEntry = "#" + arr[i];
newArr.push(newEntry);
} else {
// let newEntry = "#" + arr[i];
// newArr.push(newEntry);
}
}
// range.offset(0,1).setValues(newArr);
// console.log(newArr);
}

Answer 1

function breakapart() {
const ms = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December']
const ss = SpreadsheetApp.getActive();
const sh = ss.getSheetByName('Sheet1');//Data Sheet
const osh = ss.getSheetByName('Sheet2');//Output Sheet
osh.clearContents();
const vs = sh.getRange(1, 1, sh.getLastRow(), sh.getLastColumn()).getDisplayValues().flat();
let oA = [];
vs.forEach(p => {
let f = p.split(/[. ]/);
if (!isNaN(f[0]) && ms.includes(f[1])) {
let s = p.slice(0, p.indexOf('.'));
let t = p.slice(p.indexOf('.')+2);
oA.push([s, t]);
} else {
oA.push(['',p]);
}
});
osh.getRange(1,1,oA.length,oA[0].length).setValues(oA);
}