[consp]

In Euros maybe, it's 6k/month with 13th month, it's at higher edge but definitely not top 5%, the 50k would be below senior no matter how you look at 'senior'. In Dollars less than reasonable, especially since you do not want to be payed in foreign money if working remote. It also depends a lot on what kind of experience/education you prefer. If you want highly educated seniors with 'senior' level of experience (as in multiple years to a decade) the higher end matters a lot, NL is famous for underpaying engineers and overpaying managers and the better engineers have noticed.

Though without knowing all secondary stuff it's a wild guess anyway. What you describe in NL usually also benefits pay for pension (usually not included in gross salary specification), some form of mobility or at-home budget, and all other perks considered in-kind pay, maybe a lease-car at a larger company. Maybe that's included here, maybe it's not and that can make up several dozens of percents of pay.

Though "senior" means so little it's hard to judge what is meant by that though it looks like OP is specifying task-specific roles which lower the need for a jack-of-all trades, highly educated, years of experience a bit.