The handwritten labels could be on test pressings, or they could be instant recording/home recording discs. As noted above, photos would help.
OK, what to play, and what *not* to play, on your BN.
Do NOT play any record on the Pathé label from before the electric era unless it says "Actuelle" as well. Even after electric recording came in, look for any reference to "sapphire" on the label. Those are definitely no-nos. They were vertically cut and designed to play with a special large-diameter sapphire stylus; steel needles will quickly destroy them, and you'll hear little or no music from your machine. (For more detail about vertical vs. lateral, here's an article I wrote:
https://www.tnt-audio.com/vintage/mono-a-mono_e.html) The early ones have artist and catalogue info etched directly into the record surface and actually play from the inside out; later ones have conventional paper labels and play conventionally outside-in. They come in a mind boggling array of sizes, from 8" or so up to 20". None is suitable for your machine.
Do NOT play other record labels that emulated the Pathé system--examples include, inter alia, Rex, Rishell, and a bunch of French labels pressed by or subsidiary to Pathé, like Disque Henri, Disque Aspir, Disque Ideal, Aerophone, .... Some have the same type etched labels as the early Pathés; others have paper labels. Again, not suitable for your machine regardless. And again, any reference to "sapphire" on the label is a tip-off. If the label of a French record refers to "aiguille," which is French for "needle," you're OK.
Do NOT play Edison diamond discs, easily recognized by their ¼" thickness. Like Pathé's sapphire discs, they are vertical cut, designed to play with a special stylus (in this case, diamond). Again, no music, just noise, from your machine and quick destruction of the record with steel needles. Some Edison discs have label information molded straight into the record material; later, Edison joined the rest of the world with paper labels. The paper ones, however, were not always securely fastened to the record and not infrequently have fallen off, leaving only a blank tan cardboardy backing circle in the center of the record. The ¼" thickness continues to be a dead giveaway, however.
Do NOT play instant recording/home recording discs (possibly what you may have with handwritten labels). These had lacquer or like recording material laminated onto a metal or even glass base. They will not survive play with a reproducer like yours and steel needles.
Don't try to play "needle cut" vertical cut 78s from certain labels that later went to lateral cut, like, say, Vocalion, Gennett, and Lyric. Some very early OKeh records also fall into this category, too. I don't know that you'll hurt them, at least with a single play, but your reproducer won't give you any sound to speak of, aside from noise, either.
The good news is that you are unlikely to enounter the Pathé-type records very often "in the wild," you're even less likely to encounter needle cut verticals, and the Edisons are easily recognized.
You CAN play any standard lateral cut record from the acoustic era in conventional shellac--which is to say the vast majority of 78s up to 1925--Victor (Talking Machine Co.), Columbia (Graphophone or Phonograph Co.), Brunswick, Harmony, Cameo, Domino, Pathé Actuelle (as opposed to plain Pathé), Grey Gull/Radiex, any Vocalion or OKeh or Gennett after the earliest issues (which you're unlikely to encounter), Euorpean labels like HMV and English Columbia and Edison Bell Winner and on and on. Don't try to play records of the period that were pressed in other material, examples including Hit of the Week (a material called Durium on a cardboardy paper base) and Marconi Velvet Tone (a short-lived, somewhat flexible Columbia product aimed at offering quieter surfaces). Note, however, that Edison Bell made a standard shellac record labeled Velvet Face, and those are fine for your BN. (Edison Bell was an English company not related to US Edison or to US Columbia.)
You CAN play electrical recordings, those after 1925, as long as they are pressed in shellac, but they are not really well suited to your earlier machine. From World War II on, records began to transition into materials more like modern vinyl. V-Discs from WW II itself fall into this same category. Avoid playing those; they won't hold up to steel needles in an acoustic era reproducer. Those from the 1930s work with steel needles (even the electric pickups of the day mostly relied on them), but as time went by they were less and less engineered for the very heavy tracking force of early machines like yours, and they will tend to overdrive the early reproducer. Best to stick to acoustic records. As a rule of thumb, any Victor record mentioning "orthophonic," RCA, or having a "scroll" label (a quick Google search will show you what those look like); any Columbia record mentioning "viva tonal" or CBS; and any record on US Decca is later than ideal for your machine. Obviously, any with a label referring to "electrical process" or like words is an electrical recording.
So there you go--a set of starter tips. Happy listening!