Foma R-100 developing in LQR

Foma tech sheet says to use LQR 9-10 minuets. That works. I developed 8mm movie film of Foma R-100 Indoors with lots and lots of light at 80 ASA.
However, I have been shooting indoors in normal dim low room lights which is at best 20 foot candles Tungsten. Development has started to work at 25 minuets, not 10 minuets.
I did a bracket test outdoors on an overcast day and 100 ASA was good at the same 25 min on the same roll.
Why am I not getting more push at over twice the developing time with the same concentration and temperature?
That is what I do not understand.
Much longer developing times do increase brightness indoors and the iris has to be closed more and more the longer film is developed up to an hour so far. 800 ASA.
I just don't understand why 25 min to work indoors at 80 ASA like for tungsten and not be 160.

I'm not sure I fully understand your question. But I don't think you can push Fomapan R much at all. Reversal is not like developing negatives.

In reversal processing the first developer is extremely active and already creates very high contrast. The highlights to a scene must be developed close to Dmax, since only then will they appear clear after reversal. Under normal contrast negative development these same highlights would rarely go beyond D=1.5. Regular E-6 film sometimes allows pushing by one or two stops. I have done Provia 400X at EI1600 myself, but black&white films including Foma R-100 may not support this, and extended first development may not give you much of a push.

One way to test for this, without going through the whole reversal process, would be taking test shots, and doing negative development in increasing push steps. At some point you will get more and more base fog (which translates into muddy shadows in reversal development) but no further contrast increases. What you are trying to do is to get 2 stops underexposed areas to reach final density of about 1, which means in negative development these areas would have to reach density around D=2. You can try various modifications of first developer (higher pH or more Thiocyanate to increase contrast, more Benzotriazole to save the shadows), but there's a chance it simply won't work out.

I will do a test of 3 feet long of Regular 8mm one half outside one half inside under T lights only. No daylight bulbs allowed. Then the 3 foot strip will be cut in half to 1 1/2 feet . On Jobo 110 reels one will be developed 10 min and the other developed 25 min. Then I'll see what is what. Thanks for the replies, but I do not understand DMax at all. Never studied that. Nor can I use graphs, but I may be getting close to being able to plot one from all the tests I've done. Another test looked great at 60 minuets and 800 ASA about

The test is done and there are pictures on both parts. 10 minuets development at 68F looks dark indoors, darker than it should and outside it may be correct because it was very overcast. but still looks dark. The part that was developed 25 minuets at 78F looks much lighter, indoors it looks correct, as the room was, outside it looks light, maybe lighter than it was? I cannot tell about the leader because it is so small, regular 8mm, until I slit it and put them side by side.

What about contrast? As you extend development time, you typically increase both contrast and fog level, but not necessarily to the same degree. Are your "lighter" slides just shifted to brighter tones, or is the tonal range also stretched? What do shadows look like?

The way I judge is to project the movie film on a screen. Videos are made off the movie screen. Many are on my channel. I also take photos on a light table. They can end up on FaceBook. A scene is bracketed, using 1/3 stops, which can be clearly seen to change between each shot.
Contrast is lower in darker images and I try to lighten them by developing longer. Indoors, a yellow or off white wall looks gray and dull compared to real life when developed 10 minuets, however the 25 minuets one looks correct. The darks are judged by looking at a light bulb through the leader, which is black. I load and unload in the dark to get black leader and eliminate flashing the ends. At 80 degrees F and 21 minuets the leader became too light and thin for me. Ones like that are Selenium toned to darken them back down. Just a little because the lights also become darker, just not as fast. So, I lower the temperature and then extend the time. That lightens the wall and darkens the leader.
What I wanted to find out was how this film, Foma R-100, behaves, developed as taught and my way, shot under identical conditions.
This morning I wrote a page about the sunny 16 rule applied to what I discovered. It applies if I use 24 fps and 1/100 at f16 on a not too bright sunny day with almost cloudy bright shadows, but still hard. Not as bright as it gets. I think the film is adjusted to include bright sun on sand and show. The image is 25 min dev not 10