If our two syllable surname ends in s does that make first names that end in an s sound a bad choice? [name_f]Alice[/name_f], [name_u]James[/name_u], etc.
Depends on the name. [name_f]Alice[/name_f] [name_m]Harris[/name_m]? No. [name_u]James[/name_u] [name_m]Harris[/name_m]? Fine.
This one kinda of depends. Ultimately it’s not a super big deal but also can sound really repetitive potentially.
For example, our surname is [name_m]Harris[/name_m]. I love names like [name_f]Agnes[/name_f], [name_f]Iris[/name_f], and [name_f]Mavis[/name_f] but I think those are definitely too repetitive sounding with our surname. However a name like [name_u]James[/name_u], which was one of your examples, has a slightly different sound and so a name like [name_u]James[/name_u] [name_m]Harris[/name_m] doesn’t sound as redundant as [name_f]Mavis[/name_f] [name_m]Harris[/name_m] would. So really it just depends.
I think it depends on the last name. I feel like [name_f]Alice[/name_f] Waters or [name_u]James[/name_u] [name_m]Harris[/name_m] sound completely okay but [name_f]Alice[/name_f] [name_m]Jonas[/name_m] or [name_f]Alice[/name_f] [name_m]Harris[/name_m] both sound too similar.
Edit: totally did not read this thread and see that two other people used the EXACT same examples I did lol.
To reiterate what other posters have said, it depends.