I'm going to detail the most absurd workaround to my issue, just stay with me...
(I know my example ventures into MQA territory, but not for the reason one might expect at first)
https://www.mediafire.com/folder/u4og2u9efefzh/Test
(Folder containing 8 otherwise identical audio files, just with different permutations of metadata)
The test file itself is 16bit/44.1kHz.
Its ORIGINALSAMPLERATE tag, i.e "pre MQA" sample rate is "44100".
In all but the first test file iteration, ORIGINALSAMPLERATE tag has been edited in Mp3Tag to value of "88200"
Oversampling Ratio in Neutron has been set to 2
Encoder tag and MQAENCODER tag in test file are identical:
MQAEncode v1.1, 2.3.3+800 (a505918), F8EC1703-7616-45E5-B81E-D60821434062, Dec 10 2017 07:43:32
Test File #1 appears as MQA, playback at 44.1kHz
ENCODER tag (untouched)
MQAENCODER tag (untouched)
ORIGINALSAMPLERATE tag (untouched)
**Whenever 'MQA' is recognized by Neutron, Oversampling Ratio is ignored and ORIGINALSAMPLERATE tag is obeyed**
Test File #2 appears as MQA, playback at 88.2kHz
ENCODER tag (untouched)
MQAENCODER tag (untouched)
ORIGINALSAMPLERATE tag (88200)
**By changing ORIGINALSAMPLERATE tag, with an MQA encoded track, sample rate can be defined by user.**
Test File #3 does NOT appear as MQA, playback at 88.2kHz
ENCODER tag (removed)
MQAENCODER tag (untouched)
ORIGINALSAMPLERATE tag (88200)
**So with the ENCODER tag removed, MQA is NOT recognized!**
Test File #4 appears as MQA, playback at 88.2kHz
ENCODER tag (untouched)
MQAENCODER tag (removed)
ORIGINALSAMPLERATE tag (88200)
**Yet, with the MQAENCODER tag removed, MQA IS recognized, and ORIGINALSAMPLERATE tag is obeyed**
Test File #5 appears as MQA, playback at 88.2kHz
ENCODER tag (truncated)
MQAENCODER tag (untouched)
ORIGINALSAMPLERATE tag (88200)
**With Encoder tag truncated to "MQAEncode v1.1", MQA is recognized, and ORIGINALSAMPLERATE tag is obeyed**
Test File #6 appears as MQA, playback at 88.2kHz
ENCODER tag (untouched)
MQAENCODER tag (truncated)
ORIGINALSAMPLERATE tag (88200)
**With MQAENCODER tag truncated to "MQAENCODE v1.1", MQA is recognized, and ORIGINALSAMPLERATE tag is obeyed**
Test File #7 appears as MQA, playback at 88.2kHz
ENCODER tag (truncated)
MQAENCODER tag (truncated)
ORIGINALSAMPLERATE tag (88200)
**With truncated ENCODER and MQAENCODER tags, MQA is recognized, and ORIGINALSAMPLERATE tag is obeyed**
Test File #8 appears as MQA, playback at 88.2kHz
ENCODER tag (truncated)
MQAENCODER tag (removed)
ORIGINALSAMPLERATE tag (88200)
**With ONLY truncated "MQAENCODE v1.1" ENCODER tag, MQA is recognized, and ORIGINALSAMPLERATE tag is obeyed**
So hypothetically, one could place* this dummy "MQAENCODE v1.1" text to ANY file's ENCODER tag metadata, as well as add ORIGINALSAMPLERATE tag metadata equal to the original sample rate for any files in their library that are greater than 88.2kHz.
(*I am assuming that one does not particularly care about any original ENCODER tag metadata to any great degree)
In doing so, oversampling would be obeyed for files of 44.1kHz and 48kHz sample rate, and original sample rate would remain for 88.2kHz files and above.