"Would you believe a better magazine?"
Translation:Lepšímu časopisu byste věřily?
It appears that you may have something specific in mind. We would appreciate it if you would indicate why you believe this word order is inappropriate. To help us fully understand your position, please also indicate what word order you believe should be shown above as the main translation, and why. Constructive comments are much appreciated.
I am not Czech, but the author of this exercise almost certainly is. And I do understand your reasoning. But the English sentence is completely non-specific. Here, "you" can be a group of men, a group of women, a group of men and women, one man, one woman.... so all possible endings are accepted.
Past participles have their own rules, they are nominal verbal forms and distinguish genders. The -li ending is used for groups that includes members that are masculine animate. Otherwise you see -ly. Neuter gemder has plural -la. You should find more in the Tips about the past tense.