The other similar language to Finnish is Hungarian (that and a language spoken in Mongolia). My wife is Hungarian, so I have some exposure and I think the grammar is probably simpler in some ways (no "perfect" tenses for example), it is the spelling that probably would push it over the line.
Spelling in English is an atrocious amalgam of contributions from a number of languages. My son is learning that in school so I am getting a front-row seat to that (especially given me out of work and remote schooling). He is constantly running into places where the rule he just learned does not apply.
Oddly, I have heard the argument before that Japanese and Chinese students are at an advantage due to the complexity of writing their languages. The argument being that their brans are being trained by that to work harder. I am not sure I buy either argument.