I found the following users who may fit your language exchange criteria:

Username	Date	Post Link	Relevance	Offered Matches	Sought Matches
u/fognar	2020-10-20	Post	`5`	English (Native)	Polish
u/pink_georanges	2020-09-06	Post	`5`	English	Polish
u/tzarina_alexandra	2020-10-21	Post	`5`	English (C2)	Polish
u/pagnyx	2020-11-03	Post	`5`	English (C1)	Polish
u/greystone717	2020-09-06	Post	`5`	English	Polish

Please feel free to comment on the above posts to get in contact with their authors.