[name_u]Rowan[/name_u] (b) and Chestnut (g) - [name_u]Rowan[/name_u] works for the boy but Chestnut does not work for the girl, perhaps [name_m]Birch[/name_m] for the girl? Or [name_f]Lark[/name_f]?
Marciela, [name_f]Angelica[/name_f], and [name_f]Maria[/name_f] - These work perfectly together 
Coronia (g) and Aethra (g) - Very unique names, also works.
[name_m]Sebastian[/name_m] and Drizella - I don’t like Drizella, maybe something more traditionally posh like [name_f]Cordelia[/name_f] or Rosamobd.
[name_m]Jacob[/name_m], [name_f]Emily[/name_f], and [name_u]Taylor[/name_u] (g) - These work
[name_f]Samantha[/name_f], [name_u]Ryan[/name_u] (b), and [name_u]Morgan[/name_u] (g) -These work too
[name_f]Sundi[/name_f] (g) and [name_m]Kaedyn[/name_m] (g) - On their own they are fine but I feel like they don’t have the same theme, [name_f]Sundi[/name_f] seems relatively bohemian and [name_m]Kaedyn[/name_m] appears to be a modern trending name. Perhaps picking one theme or the other?
[name_f]Elizabeth[/name_f], [name_m]William[/name_m], and [name_f]Mary[/name_f] - Works 
[name_m]Arthur[/name_m] and [name_f]Florence[/name_f] (g) - Also works
[name_m]Charles[/name_m], [name_f]Edith[/name_f], and [name_u]Francis[/name_u] (g) - Yup
[name_m]Thomas[/name_m] and [name_f]Elsie[/name_f] - yup
[name_f]Margaret[/name_f] and [name_u]Shannon[/name_u] - You can make this work, but I wouldn’t ordinarily associate the names together
[name_m]Jonathan[/name_m], [name_m]Christopher[/name_m], and [name_u]Everett[/name_u] - This works
[name_u]Abilene[/name_u], [name_f]Eliana[/name_f], and Lealie (g) - Very unique names again that share the heavy vowel names, pretty
[name_u]Cameron[/name_u] (g) and [name_u]Everly[/name_u] - yes