Sorry, but the only way I can see you finding out the answer to your questions, is to try them!...
One can buy a smaller packet or two of Ilford papers reasonably priced, but the filters, when bought new, are quite expensive, but worth the price if you decide to use their paper also.
You might want to send an email to Ilford and maybe Foma themselves and see what their answer is. I'd be interested to hear the answer myself, as I have received prints in exchanges, made on Forma paper, and I like the results very much.
As an after thought, I have used oddments of various papers given to me over the years, that haven't been Ilford brand, and both Kodak and Ilford filters have worked with all. From this I presume that the variously branded filters are the same or at least very similar in colour.
*** Just checking the Foma website, they say the following about filters.
Note that there seems to be NO mention of having to use one particular brand of filter with a different brand of paper! ***
FOMABROM VARIANT III can be exposed in all types of enlargers and printers
equipped with tungsten or tungsten halogen lamps. Particularly suitable are devices
with a special colour mixing head for multi - contrast papers. Other enlargers can also
be used, but separate correction filters should be inserted during exposure.
Contrast control
The contrast can be continuously varied from extra soft (contrast grade 0 resp. 00) to
ultra hard (contrast grade 5). FOMABROM VARIANT III being orthochromatically
sensitized, its contrast is controlled using yellow and magenta filters during
exposure. If only the blue sensitized part of the emulsion is exposed (under magenta
filters), the contrast will increase; if the green sensitized part of the emulsion is
exposed (under yellow filters), the contrast will reduce. The following methods and
devices are recommended for contrast control:
- standard sets of filters for variable - contrast papers (e.g. Foma Variant Filters, Ilford
Multigrade Filters, etc.)
- magenta and yellow filters in colour mixing heads
- special enlargingheads for variable
- contrast papers
- colour printing filters (yellow and magenta)
- colour printers with a programme for variable
- contrast papers
-black and white printers with an inserted magenta filter for hard and ultra hard
contrast grades
Terry S