Switch from linguistics to CS for PhD?
I have a bachelors and masters in a non-STEM field and am currently in a CS PhD program. I had a similar constraint that I could not afford a CS masters degree and wanted to go directly into a research PhD. You seem like you're in a good enough position to just apply now, but given my non-STEM background, here's what I did:


I took online courses such as Algorithms, Automata, Databases, and Machine Learning. I did all the assignments and took detailed notes. I'd suggest you look into Deep Learning since neural machine translation is a hot area.
I put everything I coded on GitHub. I made sure my code was clean, organized, and well-commented. This was primarily for employers—I'm not sure if grad schools care—, but I had to pay the bills while teaching myself on nights and weekends.
I held a couple of programming-related jobs, starting as a software developer at a startup and ending as a research software developer in a bioinformatics lab. The first kind of job is good for getting your foot in the door and the second is good for publications—you might already be set on the latter.
Because of the above job, I curated my application for ML + computational biology tracks in CS departments. Cross-disciplinary labs are nice because no one knows everything and everyone brings something to the table. For reference, one professor at another school told me that he wanted to accept me but was worried about my background. This lab was extremely focused, and the school expected me to start research in that area on day one. I interviewed twice but didn't get in. I think where you apply is probably the most important variable, provided you have a solid application.
I applied to 8 schools and was only accepted by 1. Just FYI.


Good luck.