I wouldn’t worry about the title, at least at this point. Here are a couple of reasons:
1.) If it is proposed that you are concerned about how it will look on your resume at the point of accepting a job, it implies that you are concerned about the appearance of your resume. A resume is only used when applying for new jobs down the road. It won’t leave a favorable impression on the hiring manager.
2.) As a former hiring manager, I did notice when there was an implied step down in job titles. What was more valuable though was description of the job duties under each title. It never ruled out an applicant. It did bring up questions during the interview asking for clarification.
If the job title change was when going from one company to another, it rarely meant something that would raise a red flag. Each company has their own title-naming process. The smaller the company, the titles can sound more impressive. The larger the company, the titles come in all forms of levels.
3.) Is this a large company? Are there others there that hold the same title? If either apply, it may require a lot of red tape in order to get approval to change your title. The company I worked for had a department designated solely to grade job positions and select titles based upon the job requirements.
If others hold the same title, it may mean that they as well need to have their title changed. Then it really becomes a paperwork nightmare for the company.
Bottom Line: The change in companies must have been made for some reason. You were successful in negotiating the salary you desired. I wouldn’t push your luck in asking for a different title as well.