Transcribing Summer from The Four Seasons, lots of accelerando and ritardando

With musescore 2, I could just install the tempochanges plugin and use it whenever I had to do accelerando or ritardando and get a precise accelerando or ritardando as a result. But I don't think this will work in Musescore 3 yet, not until it is updated at least. Thing is, I have all these accelerandos and ritardandos in Summer from The Four Seasons. I am using a piano transcription as a tempo guide and the original score for the actual notes. Even though the original score is in 3/8 in the slow sections of the first movement of Summer and also in the part with all the tempo changes, I find the quarter note tempos of the piano transcription fit well in the Summer Concerto. With the Spring concerto, I had to raise each tempo by 20 BPM from the transcription tempo.

But yeah, I don't think I can really have abrupt tempo changes except where it says they are abrupt. Too bad there isn't a tempo change plugin for Musescore 3 yet. I hope that comes out soon.

Here are the lengths of each tempo change and the tempos:

1 measure from 120 to 150
3 measures from 150 to 100
3 measures from 130 to 200

All those tempos are in quarter notes.

And here is the pdf showing those tempo changes. Yes it is a piano transcription but I am only using it as a tempo guide here.

http://ks.imslp.net/files/imglnks/usimg/3/38/IMSLP289470-PMLP126433--tr…-tbpt70_A.Vivaldi'L'Estate'-_Violin_Concerto_Op.8_No.2_in_Gm_RV.315_piano_transcription-A2D29DD7-.pdf

Page 4 has all the accelerandos and ritardandos I am trying to get into my score right now.

Here is my score with all the notes in the section with accelerandos and ritardandos. Now I actually want it to play back those accelerandos and ritardandos. Obviously it looks like the flute notes would be the best route to go to know how much to accelerate or slow down at each note. The piano will be in sync with that anyway. Of course, I can't get a precise accelerando or ritardando this way but I can get very close.

The Four Seasons.mscz

But how am I supposed to know how many BPM to add or subtract for any note?

If you copy the text that isn't in the link for some reason, click on the link and then add that text to the address, you should be able to see the pdf I am using as a tempo guide.